Today I tried the hack mentioned on xlr8yourmac.com to fix the coma issue with our G4 CPU upgrades. The hack is to delete the file "com.apple.Powermanagement.xml". It didn't work at all on our Cube upgraded with a PL 1 GHz G4. It restored short term (<1 hour) deep sleep in our Cube upgraded with a PL 1.2 GHz G4--longer deep sleep still resulted in a coma.