Ubisoft has a history of this sort of stuff -- remember when Altair kinda appeared in Metal Gear Solid 4? Well now the crossover is in Minecraft, and it looks phenomenal.
The guys and girls at Ubisoft have put together a pretty incredible Far Cry 3 representation within Minecraft, and you can totally go ahead and download it now.
I think this may be one of the smartest tie-ins I've seen of late. It's fun, out there, attention grabbing and manages to really get folks excited about both games.
Apparently the map was put together by Michael Lambert AKA Sacr3, the creator of Newcraft City. Axel Janssen and Yohann Delcourt helped put together the textures.