This is great news! Rock band was one of the few games that had me eying a PS3, but now I'm definitely going to hold off and just wait for the Wii version. I knew it was coming eventually ("it prints money" etc.) but I'm a little surprised it's in a few months without any other announcements.
Oh, and for the record? I play the real guitar as well, and Rockband/Guitar Hero are simply fun diversions that I can play with my friends. Not everyone wants to jam or play in a real band. :p Sure, get a real guitar, it's extremely fulfulling to learn songs and become an accomplished musician. But sometimes, it's also fun to stage dive off your couch while you rock. :)