(probably this is a tech-userlevel issue, please continue
there..)

> Is there something to do the reverse, so that NetBSD can
> offer an SPP service to another bluetooth client?  The
> sync interface of my phone works this way: you tickle one
> of its SPP's and it disconnects and tries to make an SPP
> connection back to you, expecting to find PPP running
> there..

What sync software would you like to use?  I confess I don't
know much about that, is it possible that the phone doesn't
really expect to find a PPP interface to do the sync?

It is not difficult to write something that will listen on a
RFCOMM channel (and register with SDP server), maybe
rfcomm_sppd should be able to handle something like that.. 
there is a program in FreeBSD called rfcomm_pppd that does
handle this kind of thing for certain phones, but I didn't
port it because it seemed more useful for their user-ppp
daemon.

iain