Avery Guerra, who has been a good source for "inside" information on the Legendary Pictures/Warner Bros. Godzilla movie project, has this to say about the Godzilla 2012 poster:
I'll squash this before it get's any further. The poster and website are fake. They're just some elaborate prank, fan made, and nothing more. I've checked with a source close to the production and have now had this debunked. I'm sure we'll probably be seeing more such hoaxes up until the time L.P. decides to start releasing materials.
I had my doubts on the poster, but I figured I'd put it out there for everyone to see. At least it got the message boards buzzing for a little while.
Looks like we'll have to wait for the real thing.