According to a post over at 3DCenter.org, the early version of the Catalyst 11.7 had some interesting codenames of what appears to be at least some chips in the AMD's upcoming Southern Islands GPU lineup based on the 28nm manufacturing process. The new driver lists New Zealand, Tahiti, Thames and Lombok. The next generation of the AMD's 28nm GPUs will most probably use the VLIW4 SIMD design and, if all goes well, should appear in late Q3 or early Q4 2011.
The details regarding the new GPUs are pretty scarse, but for now it looks like Tahiti is the new high-end GPU that will be available in two versions, Tahiti Pro and Tahiti XT. New Zealand will most probably end up to be a dual-GPU variant with two Tahiti GPUs. The Thames is a bit tricky as this could end up to be either a performance chip or one of the new mobile chips. In any case, the Thames should appear in three different versions, Thames LE, Thames Pro and Thames XT/GL. The Lombok code name might be a direct successor of the Barts chip but that info is still to be confirmed and should end up with at least three different versions.
We are still pretty far away from the actual release of these chips but more info should start to appear sooner than later as AMD might try to push these to the market as soon as they can to get some headstart on the competition.