As usual, even though I read far less non-fiction than fiction, the leading titles I can think of this year fall into the Non-fiction category. Two obvious leaders spring to mind: FDR and Connected. Of the two, I think FDR has to get the nod. That's because while most intelligent, connected people use social networks of one sort of another, very few otherwise intelligent people I know have actually gone back and studied the history of how today's American society was built, and how one man almost single-handedly built up many of today's institutions (Social Security, the Securities Exchange Commission, etc) that Republicans are still trying to tear down (and have no real success dismantling). I think it behooves us to understand history, not just because it has a tendency to repeat itself (or rhyme, as others say), but to realize how different the world would have been if FDR had not existed. If you consider yourself a serious thinker (or are even vaguely interested in how institutions such as Social Security get built), I think you owe it to yourself to read this book. Even worse, some even believe the right-wing propaganda about how FDR caused the great depression, or how he knew about the attack on Pearl Harbor and kept quiet about it. Honorable mentions go to: The Promise of Sleep, Your Money & Your Brain, and the previously mentioned Connected.
On the fiction side, this has certainly been the year of Alastair Reynolds for me, just as last year was the year of Richard K. Morgan. Of the lot, House of Suns really stands out, but the Revelation Space series is also definitely worth reading. Honorable mention goes to Stross' Wireless, where the novella Palimpsest by itself is worth the price of the entire book.
I didn't read many comics this year, but once again, I want to point everyone to Bill Willingham's Fables. It's still the best running comic book series that exists, has no men (or women) in tights, and as far as I can tell, Willingham has never run out of good ideas.
Unlike last year's mammoth 95 book record, this year, I only read 57 books. Of course, the year's not over yet, and maybe I'll stumble onto something so amazing that it'll kick one of the above books out of ranking by the end of the year, but I don't think anyone will come away from reading any of the above books feeling disappointed.