Ars Technica's Jacqui Cheng reports that, as of March 13, Apple will end support (i.e. no longer offer parts) for the following Macs:
Macintosh Server G4 (Digital Audio)
Macintosh Server G4 (QuickSilver)
Power Mac G4 (Digital Audio)
Power Mac G4 (QuickSilver)
iMac 233/266/333 MHz
PowerBook G3 Wallstreet
PowerBook G3 Lombard (Bronze Keyboard)
But really, if you've got anything this old, you're pretty much finding your replacement parts on eBay or over Low End Mac's swap group, right? You're looking for whole machines, working or not, to cannibalize in order to keep your No. 1 running? Right?
That said, I need a Powerbook 14oo logic board, because that might be the source of my SCSI problem, although I'm hoping against hope that pulling the thing apart and checking connectors will be the real, easier solution.