Woodcrest, or the Xeon 5100 series processors, will have 4mb of dynamically shared L2 cache. Having this type of shared cache allows each core to use as much cache as it needs to handle the operations associated with its thread. Since most multi-threaded applications tend to have imbalanced operation requirements, this allows more efficient use of the cache. If both threads are demanding, the balance of cache usage will meet somewhere in the middle.