In Japan Gran Turismo 5 had a March 2010 release date set, but the title won’t make the date. Sony Computer Entertainment delayed the game and changed the title’s release date to “TBA.”
As of right now the game has a Summer 2010 release date for North America. I wouldn’t be surprised if that gets pushed back now though. Keep an eye out for updates on the NA release.
At this point I honestly don’t even remember when Gran Turismo 5 was even supposed to originally come out.