Accelerando by Charles Stross
My friend Bill handed me Charlie Stross' new(ish) book, Accelerando last Thursday, and I've just finished devouring it. What an amazingly great read! I haven't had that much fun reading a science fiction story since Schismatrix by Bruce Sterling (and that was 1985!). Definitely gets my vote for SF book of the decade, and possibly more then that.
What I didn't realise when Bill gave it to me was that the first chapter was my favourite short story Lobsters, which I read a few years ago and have been wanting more of ever since.
Even better, Stross has released the entire book under a Creative Commons license, which means that not only can you download it from his site, but you can also give it to anyone else that might want it!
Finally, the fans have used Wikibooks to create the Accelerando Technical Companion.
Awesome. Awesome. Awesome.