USB 3.0 is pretty much a must now. Lots of stuff, especially external drives are taking advantage of it's huge bandwidth.
PCI-E 3.0. This is quite mixed. Yes it will provide extra bandwidth, but with most current video cards, if you take them out of a 16x slot and put them in an 8x slot (effectively halving the bandwidth) you won't notice much performance difference, even for a high end card like a 6990 or a 590. Maybe 2% max less.
In the next month or so, AMD releases Bulldozer and Llano, which is their first core architecture change since I think Sempron back in 2001 or so. It makes them super fast, rumored to be quite a bit faster than the i7s. Just a rumor though.
The top end model will have 8 cores and be about 3.4GHz, but they are said to be better at overclocking and the overall architecture, like I said, be really good and efficient.
I'd expect they would have added benefits, mostly speed, if used with an AMD videocard as well (ATI has been rebranded to AMD now).
