From what little I've come across, it seems that SB will be a very incremental evolution in the microarchitecture. Some added instructions, quad channel RAM, up to 8 cores on a die, and some expanded turbo modes. None of this will matter except in very isolated circumstances as we're still waiting for software to catch up to yester year.
The big change for this decade has already happened with Nehalem and the introduction of an integrated memory controller, and QPI interconnect.
Of most interest to me will be the turbo capacity of the new CPU's, as that's the only thing that will likely improve performance for my applications. 🙁