Multiplayer in Grand Theft Auto is something we’ve always hoped for. While there won’t be official multiplayer support in the PC version of GTA San Andreas, a development team has been hard at work preparing for a high-quality internet-based multiplayer modification for the game.
San Andreas Multi-Player (aka SA-MP) is currently being developed for the PC version of GTA Vice City and is approximately 80% completed. Kyeman, founder and lead developer of the mod, is hoping to port the modification over to the PC version of GTA San Andreas roughly 2 to 3 months after the game release. (I’m sure you’ll have lots to do in single player mode until then)