That'd be decacore.
At Hot Chips, Intel engineer Dheemanth Nagaraj told everyone in attendance that the next server processor from the company would have 10 cores and be able to process 20 threads.
It's the next in the server EX line, the Westmere-EX, which will pick up from the Nehalem-EX using the newest core architecture. What Nagaraj declined to reveal were clock speeds or anything related to performance, other than it'll have two more cores and four more thread capability than Nehalem-EX.
According to the Register, Westmere-EX will have an L3 cache – something Intel prefers to call "last level cache" – and each of its 10 cores will share 10 "slices" of this cache, which are accessed over a bidirectional ring bus and can handle five parallel cache requests per clock cycle.
Those running Nehalem-EX systems now can maintain their current platforms, as Westmere-EX will be socket compatible with the current Boxboro-EX platform.
One feature that did not make it into Nehalem-EX due to time constraints but will be in Westmere-EX is Directory Assisted Snoopy (DAS) to improve local memory latency.
When asked why Intel is only going 10 cores when the competition has the 12-core Magny-Cours, Nagaraj said that going with 10 "gave us the sweet spot for performance and time-to-market."