Rockstar has—probably deliberately—been doling out snippets of the Grand Theft Auto V map for some time. The ultrafans on GTAForums have been collecting them and finally stitched all of them together, giving us what appears to be a map of Los Santos and its surrounding area.
[Update: This is not an official map; it's the work of fans, using an image editor. Though it was never said to be an official map, the original wording of the lead paragraph and headline could have left that impression, or vouched for its accuracy. The post and its headline have been revised throughout.]
Rockstar has said that San Fierro and Las Venturas will not appear in this game, which is kind of a bummer, but maybe Blueberry or Palomino Creek return for your hijinks with Trevor and his merry band of meth-heads.
Above, I have rotated the map 90 degrees counterclockwise (so, south is to the right) to take advantage of our image annotation feature (it only works for horizontal things; sorry.) Curious what you folks see, or think you see, (or think you will see when the game arrives) on the map. The full-size, vertical version of the map is at bottom.
The game's map is said to be larger than Grand Theft Auto IV, San Andreas and Red Dead Redemption all put together. So that's a lot of wide-open space out there. Nice inclusion of Catalina Island, too, by the way.