The first is for Xbox owners, dubbed The Trilogy, and will include GTA3, Vice City, and San Andreas together in one pack for $59.99. The second is the PS2 San Andreas Special Edition which will include the new version of the game, along with a second DVD featuring the prequel movie (previously only available if you bought the soundtrack CD) and the recently announced Sunday Driver feature.
It is highly possible and we will be updating you if any official announcements come our way. Read the rest at 1UP.
We haven't had an official word from Rockstar yet so we don't know how true this is.
UPDATE: Take Two released 2 press releases confirming this. The first states that the Grand Theft Auto Trilogy (which includes GTA3, Vice and San Andreas) will be released on October 18th 2005 for the Xbox. The price is still unknown.
The 2nd states that on October 18th 2005 Rockstar will release the "Grand Theft Auto: San Andreas Special Edition" for Playstation 2. This edition includes the full "M" rated San Andreas, the Introduction DVD and Rockstar's debut documentary film, Sunday Driver.
Links: Xbox Trilogy and GTA SA Special Edition press releases.