The cut-off for booting OS 9 was January 2003 AFAIK, that's when the iMac G4 stopped booting it - mine is a August 2003 (last of the Rev 1 800s) and it definitely won't.

Didn't they do some kooky ceremony at that Keynote with the coffin and the comedy funeral service? That gave em a grin that went twice round - was a classic Steve moment . I think he hated OS 9 almost as much as I did (but not quite).

I believe the firmware was altered on all models at that time to prevent booting OS 9. That of course caused a total sh** storm from the OS 9 fanboys but hey - we had to move on at some time...