I've been using MaemoMapper with the built-in N810 GPS for a while and it works fine, once the built-in GPS finally acquires a signal.

I've apparently lost my BT GPS unit that I used to use with the 770. Maybe I'll find it in one of my other vehicles eventually..

I need to look into the USB->Serial adapter more. My OpenTracker+ is in hand, along with my USB OTG and USB-Serial adapters, brought up GPSD and was dumping GPS data to stdout, but the serial adapter didn't want to play ball yet. I need to work out the driver issues.