I am quite curious.. I already have seen it elsewere and I like it.
I believe it's called Sketch Rockwell. http://www.urbanfonts.com/fonts/Sketch_Rockwell.htm
There's also a face called ChunkFive that's similar: http://www.fontsquirrel.com/fonts/ChunkFive
The font used is actually Sketch Block, which can be downloaded here:
Edit: Sketch Rockwell is the same font under a different name, apparently. Oops!