ok, ok...apparently no one double checks their sources here.
First of all, Grand Theft Auto 3 AND Grand Theft Auto: Vice City are coming to Xbox AND Gamecube in Q1 2004.
Sony's agreement with Rockstar ENDS in 2004, enabling Rockstar to develop on any system it wants to.
If you don't believe me, go here.
cube.ign.com
xbox.ign.com