According to the most recent rumors Google is planning to release its own version of the Virtual World Second life. The move is not all that surprising considering googles rapid expansions and its eagerness to explore new marketing and advertising channels.
According to last months speculations from Business 2.0 this is highly probable, and google would probably use its Google earth and layer it with 3-D models. After that the only thing which would remain, would be the creation of an economy and avatars (certainly within the giants reach)
The idea of having a virtual world whose terrain is based on the real world is almost too redundant for me, but nonetheless I would give it a shot.