What you need
1) Jabra BT200 for Non-Bluetooth phones: comes with its own bluetooth receiver (already matched to the earpiece), outputs as mic with 2.5mm phone plug (stereo -- one side for receiving, one for transmitting).
2) an adapter (Radio Shack) 2.5mm to 3.5mm stereo phone plug adapter (approx $5)
3) Griffin iMic, which takes a Mic In, pushes to USB (powered!) -- you already have one of these -- right?

It may be a little on the Rube Goldberg side, but it works, and if you have a non-bluetooth phone (as I have) I can use it with your phone (no need to rematch bluetooth signals).

The benefits are
a) Because I'm using Mic-in on USB instead of bluetooth, my PB 15" handles speakable items -- I can control Keynote wirelessly now;
b) No need to update firmware as described above.
c) Can use with non-bluetooth cell phones

Negatives:
i) a bit Rube Goldberg
ii) BT200 for non-bluetooth phones is more expensive than bluetooth earpiece alone.