This is Cory Doctorow's new YA sci-fi book. If you go to his website he has electronic copies of it available under a Creative Commons license. There's a great donation system set up too so that those of us who read the ebook version can get the book to libraries/schools that want it.
I really really liked it. It's one of those books that gives you a ton to think about afterwards.
It's basically a "what if" kind of book. What if a few more civil liberties were taken away, what if there was a bit more surveillance of people, a bit more invasion of privacy. The thing that's really freaky is that all the various technologies that are used in the book are things that are possible right now, they just aren't being done or at least not to the extent they are in the book. So then it becomes... how much are people willing to give up to feel "safe"? Where is the line when we say enough is enough?
Aside from the "big idea" stuff, it's just wonderfully geeky. The kids in the book use websites that I use; they do things I do (or that people I know do). And he's dedicated each chapter to a different book store! Which, to me anyway, gave the whole thing this feeling that it's a celebration of books themselves.
And don't let the whole "YA" thing turn you off, it's a very good book whether you're a teenager or somewhat older than that.