5) Lightborn, by Tricia Sullivan, a story of cyber-warfare and devastation in a near-future California. Really failed to grab me. I note also that it has much the fewest owners on Librarything (10, to 35 for MacLeod, 65 for Beukes, 189 for McDonald and 1205 for Bacigalupi).
I very much like all the other four, and while I have special reasons for my first choice, would be delighted if any of the below wins.
4) The Windup Girl, by Paolo Bacigalupi. Another near-future story about catastrophes, this time set in Thailand, the girl of the title being an artificial woman who must trade her body for her life. Won the Nebula and joint winner of the Hugo.
3) Zoo City, by Lauren Beukes. An urban fantasy set in South Africa, with necromancy, organised crime and animal familiars. Brilliant stuff.
2) The Dervish House, by Ian McDonald. Set in Istanbul in the year 2027, involves nanotechnology, arcane secrets, and terrorism on the Nabucco pipeline, in McDonald's trademark lush descriptive prose.
1) The Restoration Game by Ken MacLeod. I have a personal stake here in that I gave some advice on the parts of the story set in the fictional South Caucasus territory of Krassnia (the rest is in Scotland and New Zealand, in the years leading up to 2007). That aside, it's an excellent novel taking recent history, 70's radicalism and computer games and merging to a brilliant twist at the end.
Previous write-ups of this year's BSFA shortlist: short fiction.