This is a slide from an Intel presentation talking about the upcoming Nehalem-EX, which will be the four socket server version of the desktop Core i7 CPU. Unlike the Xeon 55xx series, this CPU will have eight cores plus hyper-threading, so you will have 16 logical cores for each physical CPU. This means that a four socket machine would have 64 logical CPUs, which makes Microsoft’s SQL Server licensing method (where you pay for physical CPUs only) an even sweeter deal.
This CPU is supposed to be available in systems this fall. I am guessing that it will be called the Xeon 75xx series, and it should perform very well for SQL Server 2008 workloads!