Higher clock speeds and a bazillion more stream processors.What about the 4870 would lead you to believe it should have destroyed the GTX260?On paper the 4870 should have destroyed the gtx 260 216, but in actuality they were fairly equal performers. I suspect this will be the same with the gtx 360 vs. 5870.
My guess is that the gtx 360 will have an msrp of $399 and the gtx 380 will msrp at $499.
Classic misunderstanding of hardware architecture... despite the higher clockrate and greater number of shaders, the GTX260 216 actually has clearly superior fillrates, yet the two GPUs perform similarly. If anything the GTX260 216 has the better paper specs.