The issue is whether or not a package should be mountable under other packages *other than* a subsite instance. None of the current packages have any functionality that makes that desirable.
I have thought about this a bit, though, and wonder if it might not be made useful in the future. For instance, being able to mount a bboard under and SDM instance might be a useful way to provide a devoted set of forums relating to it.
I think we need more discussion of this particular issue. I don't see any *harm* in being able to mount packages under (non-subsite) package instances...
