http://www.rockstargames.com/V/

and i couldn't resist.

this multiplayer looks like it could be a whole separate game itself.

Edit* swiped this from IGN

In an interview with CVG, Rockstar North President Leslie Benzies provided some more detail and context on Grand Theft Auto Online. He stresses that it's "a different entity, a separate thing, and it'll grow on its own. It'll be GTA Online; it's not part of GTA V. Obviously it's set in the GTA V engine, but it's going to grow and evolve into its own thing."

GTA Online will be available two weeks after the launch of GTA V, and will be accessible as an extra character on the "Switch Wheel", right next to Franklin, Michael, and Trevor. It won't require a substantial download, just a code.

And what does the future hold for GTA Online? Tantalisingly, Benzies said, "We've set this up so there are no limitations. The only limitation is the size of the disc and how much memory we've got. We could, if we wanted, simulate the entire world, different countries, whatever. Whether we do that or not... But we've got a bunch of old stuff that we're toying with using.