While Retro City Rampage has been in production for quite some time, it is finally releasing. Even better, buying the game once will provide you with free access to the other version.
Announced yesterday on the weekly Playstation Blogcast was both the release date for the game, which will be next Tuesday, October 9, as well as the cross buy incentive Sony is trying to push. As with most all other cross buy titles so far, Retro City Rampage will be a title that you can buy the PS3 version, and get the PS Vita version for free, or vice versa. The game will cost you $14.99 when it releases on Tuesday.
Do note that this applies specifically to Playstation 3 and Playstation Vita users, and the other platforms may release the game on this day, but it is not confirmed.