Get ready to create your own content for GTA Online, because the game's content creation tool is out today. You will be able to create deathmatches, team deathmatches, races, GTA races, and rally races. Any player created missions that are really good will be marked as "Rockstar Verified Jobs", so you won't have to waste your time playing garbage, which is really nice.
Rockstar is also working on bringing multiplayer heists into GTA Online, saying “We know many of you in the GTA Online community are super excited for the debut of co-operative Heists. Heists are currently in development and we are working very hard to get them as polished and as fun as they can be. Stay tuned for much more detail in the New Year.”