Like the subject says ;-).
The kernel on your boot images (and probably Disk Druid)
don't understand the *BSD slices-in-a-partition scheme.
It'd be nice to add that so that I could install off of
a FreeBSD slice, mount slices under Disk Druid, etc.
The same thing is true of Solaris slices, for that matter.
This issue has been put on a list of feature requests for future releases.
Moving to RESOVLED - DEFERRED from CLOSED - DEFERRED