Oh you have got to be KIDDING ME! Seriously? So Snow Leopard can no longer create an HFS disk for use with an older Mac? What the hell is wrong with them? I mean imagine ... you need to prep a disk for use with an older Power PC. I mean this is really taking the forced upgrade thing way too far. What is the harm in allowing HFS? It's simply a file structure. I have hope that if MFS could be implemented under Tiger that someone will add HFS to Snow Leopard, which (as I've pointed out) is still currently far more useful and relevant.
Thank GOD for Mini vMac. At least HFS & MFS disk images can still be manipulated. But here's a real problem. You won't be able to put files directly into an HFS disk image for use within Mini vMac. It will have to be manipulated directly within the application. But when did HFS+ become available? I think it was OS 8.1, which I don't think any 68000 will boot. This means HFS & HFS+ files will have to be manipulated in Sheepshaver or Basilisk II. What a fricking nightmare. I do believe Paul Pratt has enabled a way for files to be imported and exported to and from Mini vMac directly into OS X, so that may become a larger component of the system now. Brother ...
EDIT: I just checked, Paul's file importer doesn't import a stand-alone file with the resource fork intact. He recommends using an archive for that reason. Unfortunately, I don't think there is a good way to create an archive under OS X which can be opened under System 7.5.5 or less. Fortunately Paul is currently working on a Macintosh II emulator. Theoretically that emulator could use a IIfx ROM like the SE/30 & IIx which would allow for the use of HFS+ under 8.1. So the Mac II emulator becomes the most important Mini vMac emulator in order to maintain the original 68000 emulators. Of course Basilisk II and SheepShaver are alternatives which need to be further explored under Snow Leopard. I've already determined that some aspects of SheepShaver have been crippled by SL, like serial port access. Unfortunately neither has been touched since 2006.
Actually, not a very "special" drive. Fortunately, the UniDisk used that drive since 1985 and Apple switched to the same drive mechanism both internally and externally by September 86. So it is the most widely available 800K drive. The disabled header models were used only briefly in the Mac Plus and original 800K external drive.