GTA V Multiplayer
No details have yet been revealed about GTA V's multiplayer modes, other than the fact it will of course be a feature. What we do know is that it will build off the groundwork laid by GTA IV, and the additional features that Max Payne 3 added.
While we're yet to have a big multiplayer reveal feature, Rockstar's Dan Houser has said in Game Informer's exclusive December 2012 preview:
We're very pleased with the direction it's heading. We're ever closer to nailing the fun and excitement of open-world multiplayer.
Another aspect of multiplayer we know of is that Crews will be a feature. First debuted in Max Payne 3, the crew system allows groups of players to earn rewards and XP for winning matches and performing various feats in-game.