McKenzie Wark, "Gamer Theory," (Harvard University Press, Cambridge, 2007).
I got this book two weeks ago. I am not yet done reading, but it is an awesome read so far (am about half-way through it right now). A critical theory of games/gamers and the relationship to modern society. Lots and lots of philosophy and some interesting analysis of a selection of old-school and modern games. Extremely well written, very sophisticated. And at times it almost reads like poetry. The dude has a Ph.D. in this stuff, and it definitely shows
It encourages the reader to think critically about the relationships between gamer/game, and their relations to culture, media, history, sports, etc.
Heck, there's a whole chapter in there about "Rez"