Who says more cores have to mean lower clock speeds? Singaporean overclocker Shamino claims to have gotten his hands on a sample Gulftown processor, and he's gotten some rather impressive speeds out of it.
Judging by the initial CPU-Z screenshot, the Gulftown sample is meant to have its six 32-nm cores ticking away at a base 2.4GHz clock speed. The CPU also has 12 threads, 12MB of L3 cache, and an LGA1366 package. Shamino ran it in a high-end Evga X58 SLI Classified motherboard.
Subsequent CPU-Z shots show increasing clock speeds until page three, where the processor reached 6.39GHz at a frightening 1.92V. That feat involved a 194MHz bus speed and a 33 multiplier—the sample was unlocked, evidently. Shamino says he couldn't get the CPU stable at that speed, however, even with a voltage push to 2.02V.
Instead, the Gulftown sample seemed to be happier under the 6GHz mark. It apparently completed a 3DMark Vantage CPU test at a still-impressive 5.89GHz with 1.88V. Unsurprisingly, though, those feats involved unconventional cooling. The overclocker says his whole motherboard "got wet" at 6.2GHz, presumably because of condensation. (Thanks to Fudzilla for the link.)