The Sony Ericsson MW600 is by far the most promising of the bluetooth stereo headphones I've tried recently. The best thing about it is that it isn't a fully integrated headset with headphones. Instead, it's a blue-tooth receiver and microphone that turns any standard set of headphones into a bluetooth headphone! Yes, that means my beloved PX100 are now blue-tooth compatible, which grants me no end of delight. Now, this also means you can't be like Uhuru from star trek and hang the headset off your ear, but in practice, any set of ear buds would let you just plug one ear in and clip the microphone to your shirt/blouse so you can talk while hands free in the car or on the bike.
Pairing: the process was straightforward, and I had no problem pairing the MW600 with my Nexus One, my Nexus 7, and my desktop PC. Selecting between them is a little tricky, since the touch strip is a little finicky (and the LED display is difficult to read outdoors), but I managed it. The sound quality is nothing short of amazing. Unlike the SBH500, which tended to be finicky outdoors, the MW600 does not care whether it is indoors or outdoors. There's a built in radio receiver, which also sounds pretty good, even indoors.
The cons? The volume control is a touch strip, and is not great. The forward/back/play/pause buttons aren't clearly delimited, and can be easily confused. I expect that to be no problem as I get used to it. There are reports on the internet that the clip is fragile. I expect the last to hit me eventually, but I've got a bunch of superglue handy.
In any case, I'll be keeping this headset, unlike the other headsets I've sent back. Recommended