Is it possible to keep the serial link to the PC alive and use the other bluetooth channels (there are 7 right?) to contact other devices?
I'm not sure about that. I made a script in whitch I let the arduinoBT sitched between the INQUIRY command and the CALL command. Firts I led the ArduinoBT searching for other devices, save them in an array and then I make a CALL from the ArduinoBT to the computer to send the data back.
The problem is that you can't use the serial buffer for two diffrent purposes at the same time. So or you can send data from one to another and back (data mode) or you can look for other devices or do something else in the command mode. So it's possible to restore a connection when you write the script on the right way, but I don't think it's possible to keep to connections on the same time a live.
At the moment I'm just toying with some ideas relating to proximity marketing - sending vcards, text, images and MP3s. Do you have experience sending these items?
Doing the proximity is not that hard, I have used it a couple of times already. You let teh arduino search for other deveices in the area(command mode), save them in the eeprom or an array or someting. Switch back to data mode and restore your connection to a device or use the data later.
For sending data from teh arduinoBT to other devices, I have only used text and other simple data. The problem is the serial bufer from the diffrent deveices, especially when you want to send data to the arduinoBT. Another problem with mp3 and vcards is the internal memory from the arduinoBT, it's simly not big enough to hold your code and a big file that you want to send.
At this time I'm trying to get a sd card running to enlarge the memory from the arduinoBT but no luck this far.
If you get the hardwire working so that you can use more then one Bluethooth channel please let me now.
I hope this helps