Thanks to Matt Haughey, Leonard Lin, and this Apple document my Powerbook G4 (867 MHz) is once again running at 867 MHz.
I just last evening upgraded to 10.2.8 figuring that all the quirks have been flattened by now. Silly me. Less than 24 hours later I read that 10.2.8 may have reset my cpu frequency to a figure 2/3rds of its rated speed.
Running the sysctl hw.cpufrequency command in the Terminal I discovered to my dismay that my CPU was running at a mere 667 MHz. Following Apple’s directions I reset my PMU and restarted my machine. Once again I am running at a full 867 MHz.