New Opteron and new desktop Phenom or Agena FX CPUs will be able to hit 2.8 GHz. The new B2-Strepping will let AMD to get to 2.8 GHz with the normal TDP and to get close to the limits of Core 2 Quad frequencies.
This will have to be sufficient for AMD for fight Intel's soon to arrive Core 2 Quad Extreme QX6850 with FSB 1333 and 3 GHz clock.
Agena at 2.8 GHz has to beat this CPU and we know that clock by clock K10 wins over Core 2 Duo but Penryn 45 marchitecture will enable some high clocks beyond 3 GHz, at least to 3.5 GHz if not even higher and AMD wont be able to fight it with the current clocks or it is going to get very tough for DAAMIT.
It will be very tough and interesting in the next few months for AMD.