I just upgraded my kernel from 3.6 to 3.7-rc3 and wondered why CnQ stopped working at all, so I looked into the boot messages and found:
powernow-k8: this CPU is not supported anymore, using acpi-cpufreq instead.
As I didn't had acpi-cpufreq compiled into the kernel the issue was found.

Not sure if I would call that a bad thing through. CPU is:
model name : AMD Athlon(tm) II X3 455 Processor