I have a Nokia BH-501 A2DP headset which has a mic. The sound quality is very good and the best thing is that the power adapter that comes with it is compatible with the N800. I wish one day I could use it with the N800 so I only need to worry about one power adapter.
I have been waiting for this, too. Yesterday I finally decided to install scratchbox and to my surprise a fresh CVS checkout of plugz (and sbc) compiles out of the box. Even better, after copying libs and binaries to the N800 they actually worked.
CPU load was high but playback was without pause. I have a Jabra BT620.
It was somewhat tricky to actually find a player where the alsa plugin could be selected for output. The only thing that worked for me was to use mplayer, select sdl for output (after setting environment variables that in turn tell sdl to output to alsa:a2dpd) and to play a file format which is _not_ supported by the dsp-engine. 44 kHz, 2 channel ogg played well.
I need to find some documentation on how audio is generally handled in maemo to make this more useful. Any pointers on how esd, gstreamer, alsa, dsp are interacting on the N800?