I'm with noodie pooh (that sounds a bit strange
).... Be very interested in a group buy for the X5, a very flexible unit. Dunno if it'd be any good to talk on while riding (helmet noise) but honestly, I'm not interested in having a phone conversation while riding, but I am interested in stereo wireless connection to a PDA, MP3 device, and emergency phone use without having to waste time ripping the helmet off.
The sender unit (for non stereo bluetooth devices) wouldn't be too hard to setup, you could just rubber band the thing to your device and slip it in a pocket. More "permanent" fitting wouldn't be that much harder, I reckon I could setup a system that would allow charging via the car charger supplied, but it would be unique to each bike/device. As for permanently fitting the 'phones to a helmet... dunno, be too risky on splitting the speakers from the strap, and from what I see, you need access to the right unit for control. I know that a similar sized set of wired 'phones fit into my Shoei easily tho.