From what I understand the problem with overclocking is the extra voltage fries the cpu (slowly from the overclocking experiences here)
Would it be possible to write an app to force a scale down if the cpu was overclocked for more than X cycles?
e.g. if it was stuck at say 800MHz for more than 0.5 sec then force the max to 600Mhz, once it calms down again put the max back to 800MHz.
(tuneable of course)

I am figuring that this would probably be better done as a kernel patch, and interact directly - otherwise the app itself could cause more cpu to be used if it is called every 0.1 sec, but maybe not?

Thoughts anyone?