The problem that I see is that a lot of the people who are interested would probably want variations. For example, I wouldn't need the Oncore/Trimble support since I have a nice Garmin GPS16 so I would really just want a loose serial port.


Yeah, that is accounted for...
1 UART on the PIC - 2 wire only...so I *think* that'll be put to the empeg, since the empeg doesn't have any hardware handshaking lines.
4 UARTs in the 16C554.. 1 labelled as PC, for attaching a laptop or other PC to...this will basically be equivalent to the existing empeg port. 1 for the OBDII. 1 labelled as GPS that is connected to the internal headers. There's no major reason why these connections couldn't also be brought out via the MAX chip to an external connection, it'd probably involve a couple of hardware jumpers. (or solderpad jumpers). That still leaves one that will be labelled as 'external' that can be used for whatever purpose, radar detector, or G-Force meter.....this will probably have the full RS232 hardware capability for flexibility.

Bluetooth is really a non-starter for this project... at least as an integrated device. I don't want to have to deal with any RF issues, I have very little knowledge of the technical details, and the technology itself is still immature. But if there's a serial<->bluetooth adapter available, then maybe that could be used on the external port.