Done!
I have uploaded a video to youtube. Unfortunately I have not started the proper install in the car yet as I have still to make the skin for RR. But I hope the Video gives an idee of what you can do. Once installed I will make another video for sure.
http://www.youtube.com/v/CSKjx64AZN8
I have also made a video of its GPS receiver dead reckoning functionality
http://www.youtube.com/v/7CWpugLGUjU
The pcb can be assembled for GPS only, IBus 8051 system only (6 output, 3 inputs) or both. IBus does not have to be used, it can work with 12V inputs only for on/off and reverse.
Boot and shutdown timings are configurable via serial interface and hyperterminal or alike. You can have source code to modify too, if you want to. But then you need the $69 IDE from Silabs to be able to reprogram it.
If you want one, let me know. If there is interest I will make a new layout to sort some small issues out, but also to add a second IBus interface so that the PC can use that to get IBus events from. (still a single USB cable, but both GPS and serial COM device on it) I do not know what the price will be as I will only check that out if there is a reason :-)