Russell,
I experienced this with an early 2008 iMac.
We changed the RAM and then the logic board because of the CPU1 alerts in the report, neither made any difference. We then tried running it from an External Hard Disk which reduced the frequency of the panics. Only after replacing the internal hard drive (which tests fine) was the problem cured.
There have been a number of instances where a computer is fine running anything up to and including 10.7.3 as soon as its upgraded to 10.7.4 or 10.8 - masses of kernel panics. It tried reverting this iMac back to 10.7.3 but that didn't help, by the way.
Chris Webb . Principal