> BTW, I wouldn't say that mkfs "trashed" the root partition. The only 
> thing I can definitely say is that it can't boot afterwards, and it 
> crashes end leaves me in the debugger during boot. That certainly seems 
> to indicate that it at least affected the root partition.

Did you try to re-install the kernel and the stuff?  Can the Installer
mount the root partition?  How about booting off a kernel file on the
MacOS side in the single-user mode then fsck'ing the partitions (that
is, of course, if fsck's executable file is intact)?

ken