Source
From the update:
The first of three big updates...
Four new themes are available. Bunker, Citadel, Dwarven Stronghold, and Con-Am 27 (let's see who gets the reference first). These are prototypes and subject to some changes (and improvements - so if any of these interest you and you'd like an idea incorporated, send it along).
Big update #2 will show off the last of the themes - Gothic, Colony, and Egyptian.
Big update #3 will introduce the DIY rooms