AMD is working hard to make their clock speed relevant again with their latest Shanghai architecture for their Phenom II processors. In fact, these quad-core desktop processor chips bring official clock speeds up to 3GHz and make it so 4GHz is possible overclocking while just using fan cooling alone.
Extreme cooling methods improve performance even more. Dry ice as a cooling method provides for about 5GHz and liquid nitrogen provided 6.3GHz. These are some seriously impressive improvements, if you ask me.
Apparently, they were made possible by decreasing the size from 65nm to 45nm, which reduced heat and power usage. You can expect the Phenom II to be released early next year. It should be interesting, because this will definitely relight the flame beneath the AMD/Intel competition. AMD has the whole budget thing on it's side, too.