> What work needs to be done to allow this?

There was some work done on this (on the kenh_ifdetach CVS branch); it
needs to be merged (kicking and screaming, since it's sort of old)
into -current.  it's on my queue of things i want to get done, but
it's not all that close to the top so if someone else wants to run
with it..

Unfortunately, it involves tweaks to just about every network device
driver since it means that the "struct if", which is currently usually
just inline in the "struct ethercom" in the device softc, has to be
moved into a separately allocated structure so the softc can be
deallocated at device detach time while there are still references to
the struct if from mbufs all over the known universe...

					- Bill