Wow, those are cool looking.
Here in Cali they are really pushing the hands free sets for driving safety. I have tried to use one of those ear bud things, but noticed that it was more dangerous for me to pull the thing out and untangle the wire than it was for me to just make the two minute call in the usual way.
This would (probably) fix that problem. But it looks like something I would totally lose in my car. But I guess that's my own problem.
Now a question. If the sound is digitized, wouldn't it also be encrypted for saftey? I mean, your cell phone is supposed to be 'encrypted', so why would you just retransmit it over an insecure setting? SO, if it's encrypted how the hell are you supposed to "interface it to the computer" as Skraggy_uk suggested? Were you speaking of using a Bluetooth WLan card? or some other method?
The only way I could see it is if you hacked one of the transciever modules, and had it output to your mic line or line in on your sound card.
On the plus side if you did hack the transiever module, you could have the computer output directly to the headset via an unused output line (such as suround sound, or an extra sound card). So you could recieve voice commands and whatnot from the computer, without interupting your music, or your passengers.
Sorry if this is incoherent, I'm still hung over!