Nominations for the Hugo awards are open. If you want to find out what's eligible, there's a handy Livejournal community for sharing recommendations. (Disclosure: I am not a member of this community and have nothing to do with it.)
For my part, I only published three eligible works in 2012 ...
* Short story: A Tall Tail (Tor.com)
* Novel: The Apocalypse Codex (Ace)
* Novel (collaboration with Cory Doctorow): The Rapture of the Nerds" (Also: Free ebook download here)
Darn, they give a lot of Hugos out for fan related activities. I remember reading anthologies of Hugo winners and thinking Novelettes and Novellas had an easier time of it because the competition is thinner there. The Nebula is author awarded and the Hugo is fan related, but what exactly is the process...ah, (checks link) members of World Con would know.
Also, wow, two blog posts in one day?
I do hope that you are nominated for all three. I guess that I would pick The Apocalypse Codex if there was only one possibility.
The Apocalypse Codex has me itching for more, whereas the previous Laundry novels allowed me to have a breather in between. I would like to see it win something.
However, if you finish Palimpsest, you win at life. It still remains the only book that I think about a little every day.
If you finish Palimpsest, I'll personally deliver two black and white kittens to your desk drawer, for fun writing time. Pink paws, pink noses, and the ability to stand on their hind legs for long enough to steal things from your hand.