Google Voice + Gmail Calling?

Internets! I need your help!
I use Gmail a lot, and just signed up for a Google Voice account, which has me thinking: I'm currently paying somewhere around $70-80 a month for my cell phone (which I use for home internet  as well), and I'm wondering if it would be worth dumping AT&T entirely and going over to Google, putting some of the money into getting internet at home (which is becoming increasingly needed) and getting a cheaper pay-as-you-go cell phone or jailbreaking my iPhone to do something similar.
A couple of questions for those who've used / done this sort of thing.
- How is Google Voice, and how do people use it? As a hub for any number of phones that you might have, or as a dedicated phone line? How's the quality?
- Can Google Voice be linked to Gmail?
- Can I concivebly jailbreak my phone and get a cheaper phone plan (small number of minutes, no data) with another phone company, or would it be worth buying a cheap pay-as-you-go phone and keep the iPhone as an iPod with a couple of apps on it? - Security-wise, what are the concerns?
Currently, I spend around a thousand a year on my phone. It's been a good investment for me since I got it about a year ago, but at the same time, if I can consolidate bills down to something much lower (or down to nothing, as Google Voice is free) that would be much more preferable, especially if I have wireless that can replace it? Given that my iPad and laptop would be a far more preferrable web browser than the tiny screen on my phone.
With the introduction of my iPad to the household, I've been using my phone differently - fewer games, more productivity and reminder applications (shopping lists, writing log, dictionary check book, etc, in addition to the text messages and phone calls that I get. The iPad has begun to handle most of the heavy duty writing (not that I did much writing on my phone), games, newspaper reading and when I can, web browsing.

Question for iTunes savy people

For some reason, my computer lost my computer's music library - the music is still there, but the playlists, playcounts and ratings, all gone. I've got around 4000 songs on this computer, and it syncs my iPhone, so I'm rather annoyed about this. Annoyed is a bit of an understatement at this point, because it's a long process to recreate everything the way that I had it. I learned, a little too late, of a way to use the .xml file in the iTunes folder to recreate the library - by the time I'd learned this, I'd already begun to rebuild everything from scratch.
While looking in the iTunes folder, however, I see that there's a ton of .tmp files, and I know that they're there to recreate part of the library. Does anyone know of a way to recreate the library from these files?
Or alternatively, does anyone know of a way to recreate the library from what is still on my iPhone?

iPhone

The future is here, I'm sure of it. For the past couple of years, I've owned a variety of Apple iPods to keep up with my growing interest in music. Looking back at my record with the devices, I'm a little surprised that I actually stuck with the product - since my first one, I've gone through five. Two 3rd generation Classics, 2 2nd generation Nanos and a 2nd generation iPod Touch, which has since been swapped out for an iPhone. Fortunately, I've only paid for a couple of these, because of Apple's fantastic warranty, which covered the first couple devices when their hard drives broke.

I resisted the idea of buying an iPhone for a while, which was one reason why I bought the Touch from a fellow 501st member earlier this year. That was where I realized that there was quite a lot to these devices, and partially the reason why I went out and got a phone. The sheer functionality of the two devices have been a very interesting one, and I believe that it's something right out of science fiction.

I'm finding that the iPhone is an invaluable tool - just carrying it around with me allows me ready access to my calendar, a camera, my e-mail, a calculator, notebook, dictionary, thesaurus, first aid guide, an e-book reader, maps, a compass, the weather, and the internet, among other things, as well as being my phone and music player. I'm slowly getting into the habit of tracking my bills, 501st and work events, concerts and a bunch of other things by using it as a planner, while noting down my food shopping list, interesting books as I browse and looking up the occasional word when I come across something I can't readily remember.

Essentially, what I can hold in my hand is an entirely new method of communicating with the world. I know I'm preaching to the choir here on the Internet. But I'm absolutely astounded that I can check my e-mail, various discussion forums, the news, weather and so much more, practically everywhere I go. (Given AT&T's crappy coverage of Vermont, my options are pretty limited in places). Thinking back to my family's first mobile phone, a clunky, bulky thing that could hardly be put into a pocket, and could only do one thing: call another phone. Here, calling another phone is almost an afterthought.

Star Trek is largely credited with the idea of a hand-held communicator, and the idea has been used throughout the SF genre for years. Taken back to the 1960s, an iPhone, even without having any form of cellular network to operate on, would still be a pretty handy device - it already would be more powerful than the Apollo spacecraft, and considering that the computers of the time were the size of a room. No wonder that the idea of a handheld, wireless communications device would have been a radical idea at the time, and even throughout the next couple of decades, this sort of thing can be used as a prop in the genre.

What interests me more is that for such a rapid development in our society, the influence of something such as a smart phone doesn't seem to make its appearance in Science Fiction as prominently as it might have been. During the Golden Age of Science Fiction, the knowledge that someday, people could walk around, constantly in contact with one another via an impossible technology would have made prime story material for some of the authors. Indeed, some of the effects of these devices would probably fulfill some science fiction authors worst nightmares about a healthy society. The declines in reading, the mutilation of reading and writing abilities, the shorter attention spans and other, similar troublesome trends that we are seeing now help provide the need for such devices.

I for one, have noticed the changes in my own behavior with my phone. Before, I existed without internet at my apartment, although I could check my e-mail on my prior phone. I didn't have television and most of my news updates came from my commute to and from work. Now, I find myself checking my messages every hour or so, while being able to access an incredible amount of information whenever I think of it. Should I want to learn anything about the Faroe Islands (an island group in Northern Europe between Norway and Iceland), or if I need to look up the meaning for the word 'causerie' (light informal conversation for social occasions) or tomorrow's weather, (Mostly sunny, highs in the mid 70s, Light and variable winds...), I have it at my fingertips. I've made a conscious effort to fill my phone with things that are useful, and as such, I've found that in this regard, the phone is a very powerful tool, akin to the Hitchhiker's Guide to the Galaxy, or the Encyclopedia Galactica. But at other times, I just want to put it away, and just read a book.

Unfortunately, the phone has that covered. I downloaded the iPhone's version of Amazon.com's Kindle technology, which further adds to its already impressive array of uses by turning it into an ebook reader. I've downloaded a handful of the free offerings from the website. I'm currently reading Mary Shelly's Frankenstein, Naomi Novik's His Majesty's Dragon, Kim Stanley Robinson's Red Mars and China Mieville's Perdido Street Station, which is sure to keep me occupied at the next time that I am stuck in a line or away from my books. I can't say that I'm sold on the idea of an ebook reader, but with the option, and the occasions when I've found myself away from whatever I'm reading, I find it to be incredibly useful.

A couple years ago, this sounded like something out of a science fiction novel or film - the advances in technology and miniaturization over the past couple of years has the potential to change how we learn, access information and communicate with one another, but it doesn't change the way in which we interpret that information - it just gives us more and more as people's appetite for information over knowledge increases, which I find more worrying. I like to think that I have customized the programs in my phone be of use, for communications and information access, as well as for entertainment, and as a result, it's by my side constantly. It's handy, but I'm happy that there is one feature on it that has been a staple of all computers since their creation: an off switch.