A rumour (and we stress, a rumour
) on a website called PS Insider suggests that Rockstar may be working on a deal with Sony to allow downloads of all of their earlier GTA games on The Playstation Network.
They mention no sources whatsoever, and incorrectly explain that the PS3 would be the only console to be able to play ALL GTA Games (err... Apart from GTA Advance, Chinatown Wars, Lost and Damned and Ballad of Gay Tony...).
But anyway, if you want to jump on the GTA speculation train, head over and view the article at psinsider
Personally I think they just made up the whole thing, but you can decide