Why do you ask? I have a blueant on the way.
Well, I have a blueant q1 and when voice activation came around with 2.2 it worked differently. Not really in the way the OP stated, but it works like this:
Long press: Say a command. "Contacts." Accessing phone's internal voice command(or something like that) then it would go through the usual procedure by phone.
Trouble with it was with the Q1 I had I couldn't hear the person on the other end of the phone no matter how loud my volume was turned up. I could barely hear them. I bought a Plantronics headset for 40.00 and no problem at all. This was all with the D1, it's important to point that out.
I've never tried hooking up my q1 with my D2. So I don't know how it will work with the D2.
I'll guess you''ll find out. Just remember when it says say a command to say contacts. That's the toughest part to figure out.