Normally. you keep upcoming things out of driver releases but some programmer or a group of them didn't deem it necessary to comment out a listing of video cards that have islands as their code names.
VR Zone has a listing
of a bunch of cards that are hidden in the 10.8 drivers such as Cayman and Antilles with the numbers being in the 6XXX range. Right now, AMD has cards out in the 5XXX series so these are the code names for the next iteration.
The numbers don't mean too much since you can deduce what they are going to be based on past history of releases from AMD. Still, that's a pretty long list of 67XX cards that looks like they have in the works and that's usually more of the higher range cards.