Another photo with a close up of the the board shows "Pre-order now - Spring 2013", putting the release date between March and June next year. It's also worth noting that the promo only shows the Xbox 360 and PS3 logos, leading us to the unsurprising conclusion that Rockstar will once again release a PC version later on in the year.
While most "leaks" are in fact not leaks and simply faked items of media or information that we don't bother posting about, this one does not appear to be fake. It does look pretty legit, and given the fact that we're expecting a lot of new info very shortly, the timing of this makes sense. One would expect to see promo pieces like this up in stores in the coming weeks, and we imagine an official announcement on release timing will be forthcoming from Rockstar themselves some time very soon.
Source: GTAForums thread