R* said that theres No multi player...but now there saying theres a co-op mode.
Spong, a relatively small gaming site were lucky enough to visit Rockstar's headquarters in the last few days and view a preview of the game. As you'd expect they asked about multiplayer in San Andreas, but were told there is no multiplayer. What they did find out is that eventually you will unlock the ability to do some co-operative missions with a character who will be controlled by a second player. There's not too much information on this, although it could be* a brand new huge feature made public just days before the game is released.
* From reading their article, it really doesn't make too much sense as to how they know all of this, but it could very well be true. Make your own decisions until we have official confirmation.
QUOTE (SPOnG.com)
There will, however, be a dedicated co-operative mode for two players. During the game, a scene ensues when the player rescues a girl from a burning building. After this act of gallantry, she becomes your in-game girlfriend and also, a playable second character. Most of the co-op action takes place inside vehicles, with player one driving and player 2 shooting. When the co-op mode is opened, icons will display the missions available to two player on the game's map.
What's more, a plethora of two-player minigames will be included in San Andreas. Unfortunately SPOnG has no specific details regarding these right now, though we can confirm that various parlour games will be included.
Source: Spong.com