Sandy Bridge- EP with 8 cores is only going to be available as a Xeon processor and intended for servers. The i7 version is only 6 cores. Not that big of a deal considering there are already ten-core Xeons (Westmere -EX) available.... of course, they are $3,200 for a 2.0 Ghz model (Intel Xeon E7-8850) and there aren't motherboards out for these existing processors yet. Motherboards for them are likely to be server boards only, considering that this already happened with the 8-core Nehalem based Xeons that came out last year. Expect the 8-core Sandy Bridge-EP to be the same... i.e. nothing to worry about because you can't build a workstation using them.
And here's my prediction for the Bulldozer architecture: It will not show much significant improvement for audio processing over the current AMD architecture in most DAWs because Bulldozer is doubling the number of integer processing units in a CPU core and most DAWs and most VSTs are processing audio using floating point processing. As someone with years of experience in software that is even more intense in floating point than DAWs- namely, 3d animation software- I can tell you it will speed up the UI but not actual processing. The Athlon- i.e. entire AMD architecture- processors were very competitive with Intel processors from when they came out until very recently for 3d animation because they had a dual-issue FPU.

And those two 128 bit FP units (Flex FP as AMD calls them) can be combined to proccess a 256 bit FP instruction for say, AVX instructions.