Let me chime in with some rumours ive heard from somewhere. Believe me if you want to, else dont

Cayman will be the 6810/6830/6850/6870 (yes, four based on Cayman) to be released in November. The 6870 will be around 10 - 15 % faster than the GTX480, have clocks of 900/1500 and have 2GB memory.

Barts will be very similar to Cypress but on a new PCB and different clocks, maybe some SP's disabled and have 1GB memory.

Turks will be very similar to a Juniper but again on a new PCB and with different clocks (possibly higher).

Hmm.