The 2013 Hugo nominations (for books generally released in 2012) have been announced, and the nominations are:
Best Novel (1,113 ballots)2312 by Kim Stanley Robinson (Orbit)
Blackout by Mira Grant (Orbit)
Captain Vorpatril’s Alliance by Lois McMaster Bujold (Baen)
Redshirts: A Novel with Three Codas by John Scalzi (Tor)
Throne of the Crescent Moon by Saladin Ahmed (DAW)
The only one of these I had heard of before was Scalzi's Redshirts, since he constantly talks about his work at his ever-popular blog, Whatever. I know that Lois McMaster Bujold has won a crap-load of times and that 2312 is supposed to be brilliant.
I really have no dog in this hunt, so I hope the best book wins!