Here's a question: Say I pop a pc-card into a laptop running
NetBSD (1.5-ALPHA2 or -current).  If dhclient dhclient [or dhcp] is
already running, will it notice the new interface and solicit [or
respond] for an IP address?

If not, what's the best way, short-to-medium term,to make them (or
other apps) do so?  Listen on the routing socket for messages
indicating new interfaces, or what?

Yes, I know there've been discussions about various kenel-to-user
event notification mechanisms for years; I'd like to work on that
sometime, but I need something  now-ish...