Complete Leviathan: Index Space Marines & Tyranids! Bonuses include League of Votann, Knights (both flavors) and Genestealer Cults. Anything else you find is WIP.
As Lone Wolf has not gotten back to me you will have to add an alternate update list (At AB launch or File->Switch Game System / Select a Game -> Get Updates -> Add Source) from this link:
http://dl.dropbox.com/s/1m618itx14d73z7/ab40k10.xml
Restarting AB is necessary after adding a new source. You should only need to do this once.
Homer