MacFixIt reader John Wolf notes an interesting new feature on the PowerBook G4 15" (FireWire 800), and possibly other models, where FireWire target disk mode can see what is in the optical drive:
"I accidentally fired up a 15" PowerBook G4 (FireWire 800) in target disk mode with a CD in the drive, and both partitions on the laptop hard drive showed up, as well as the CD in the laptop.
"Ejecting the CD from the host computer works as expected, the CD is spit out. I had hoped that disc burner would see a blank CD when inserted, however, it just comes up with the "There are no volumes readable by OSX" when you try it. Apple System Profiler quits unexpectedly if there is a CD in the TDM laptop, so I couldn't figure out if it sees it as a HD volume, or as some form of Firewire to IDE bridge for the DVD drive. My guess is the former.
"It may not have broad appeal, but it could serve as an emergency CD drive, or maybe a DVD drive to another computer that doesn't have one."