My PL-380 has undergone major elective surgery (see my new album in the photos section). The results are quite positive, adding a stealthy second brain! Unfortunately, the new brain is a couple millimeters too big. The short-term solution was to remove the patient's speaker. Everything else then fits beautifully. I'll have to put some thought into re-fitting the speaker later.
What can a PL-380 do with two brains? Here's a quick sampling:
1) Full USB interface, compatible with Silabs' EVB GUI software and with "homebrew" software. 2) I've rewired the PL-380's "Alarm" button so it can initiate stealth commands. 3) An added bicolor LED provides feedback. 4) The new brain can automatically override radio parameters (e.g. soft-mute) even without USB connection.
Now to work on refining the software...