Intel revealed at the IDF in San Francisco that it will ship 10-core Westmere-EX server processors in the first half of next year:
Unusually for Intel, this monster server CPU will not require you to build a new system from scratch. Instead, Westmere-EX is socket-compatible with the existing Xeon 7500-series, so you should be able to drop one Westmere-EX, or more realistically four CPUs into your existing servers. You will probably have to update the BIOS of your server's motherboard, however.
The increase in core count is mainly possible because, unlike the Xeon 7500-series, Westmere-EX is built using a 32nm, rather than a 45nm manufacturing process. This means it should have a similar TDP to the older CPUs, although this hasn't yet been confirmed by Intel.