We've seen Phenom II, Deneb overclocked all the way to 6.2GHz. This was not a screenshot boot, we've seen it with our own eyes, as chaps from AMD managed to run the Crysis benchmark several times. The machine was stable on almost every run.   

AMD was insisting that this was a stock CPU, not a cherry picked one, and that similar scores should be expected from retail products. Intel has never managed to get to over 6GHz and we are sure that Intel is doing some catching up. You naturally need some LN2 to get to such a high scores and it looks that Phenom II might become an overclocker's favorite toy.

This is quite an achievement and with water you will get to 4GHz+, while with a good air cooler you should reach clocks around 4GHz.