Not many details have been made available thus far, but from what is being rumored things don't look as promising as one may hope. This is mostly because the Radeon HD 6000 will be based on the same 40nm manufacturing process as their predecessors. Turns out AMD originally planned to build its next generation GPUs using a 32nm process, but after TSMC skipped its 32nm R&D and advanced directly to 28nm R&D, the company was forced to adjust its plans accordingly.
We still expect the new cards to perform faster than the current Radeon HD 5000 series; they just won't exactly be a cause for rave and awe it seems. Parts based on the newer 28nm manufacturing process are coming sometime in 2011, but AMD will make sure to have something fresh on store shelves for the Q4 2010 sales period in order to defend its growing market share against Nvidia's aggressively priced GTX 460 and whatever else they have in the making.