At the end of 2009 you can expect the first 32nm CPUs that are derived from the Nehalem microarchitecture. Intel calls this tick step Westmere and this is an optimized and tuned version of Nehalem microarchitecture just done in 32nm process.
This means you will be able to add more transistors and reduce TDP and probably add even more than current maximum four cores.
This new CPU will have vast improvements but it will lean on Nehalem micro architecture. We got a confirmation that Westmere 32nm generation will reduce latency in virtualization transition and this is something that Intel did with every single generation in tick tock development model.
This model means that every second year Intel comes out with a brand new microarchitecture and a year after, you have a minor tune of the existing core, shrunk to a smaller process.