AMD's struggle against Intel for CPU dominance had them facing numerous setbacks, including ones aside from process reduction issues and performance per clock. They also faced clock speed issues, with Intel passing the 3GHz mark for desktop CPUs and AMD somewhat stuck in the mud. AMD's newest K10-based dual-core unit may change that, with the 45nm processor hinting that it is capable of speeds higher than 3GHz.
The CPU is due in the first half of next year, though how much higher than 3GHz it can go isn't known because specific clock speeds are not available. AMD's venture into 45nm should definitely come with speeds above 3GHz though, as there's no real reason not to and they have a lot of ground to cover. Numerous existing AMD CPUs can already go over 3GHz with overclocking, but a factory stable CPU above 3GHz could open the door for AMD to compete neck and neck with Intel when it comes to clock speed.
Update: This article refers to current K10 architecture-based CPUs (Opteron, Phenom). Let's remember AMD did go past the 3GHz clock speed mark with the now older Athlon 64 and Athlon 64 X2.