Mac OS 9 and Powerbooks
While there was some indication that Mac OS 9 booting would be spared until mid-2003, with Apple's release of the 12" and 17" Powerbooks, Steve Jobs made it pretty clear that these new machines would not boot OS 9 during his keynote speech.
PowerPage provided some further details from a user who had spoken with some of the Apple staff:
After talking to four different Apple staff / officials, they all said that the new powerbooks will NOT be able to boot into OS 9 whether it be from internal drive, external drive (firewire/usb), or CD-ROM. This has got to do with the boot firmware being "slimmed down" and optimized for OSX performance (e.g. booting?). Unable to perform the tests myself without getting into trouble.