The SuperDrive in my PowerBook failed recently. Attempts to query the drive from System Profiler (disc burning), mount disks, or interact with the drive in any way cause the calling application to just hang in an unkillable (E/zombie) process state.
I'm planning on buying a new drive, but in the meantime, I figured there must be some way to disable the drive from software. I didn't want to screw up my machine just by accidentally opening up the System Profiler, and I didn't want to take apart the laptop and disconnect it. I couldn't find any documentation on how to disable the inernal drive via Open Firmware's nvram settings, but I did find one approach that actually worked: removing the IODVDStorageFamily extension (IODVDStorageFamily.kext bundle) from /System -> Library -> Extensions.
I simply created a new folder called DisabledExtensions and dropped it there. There's also an IOCDStorageFamily extension, presumably if you're using a plain-old CD-ROM drive, you'd want to nuke that one.
After moving the extension, I rebooted and confirmed that the drive no longer showed up (nor did it cause hangs) when opening System Profiler or other applications that want to interact with the optical drive.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051203235221135