UPDATE:GTA Online is now live on Xbox 360. It is expected to go live on PS3 at any moment.
ORIGINAL STORY: Rockstar reckons Grand Theft Auto Online will go live and 12pm today UK time.
The game will be made available to owners of Grand Theft Auto V via what is described as a small title update” on both Xbox Live and PSN, although Rockstar warns that the launch timing is contingent on both Title Updates becoming available on each console's network”.
GTA Online will then be accessible from the bottom character slot in GTA V's character menu.
A few other details about the add-on have been released, too, including that fact that it's a prequel to main game's story, set a few months prior.
There's plenty more where that came from here.