Man, this thing has been a lot more popular than I expected.. I thought a few people would check out the server for a few days after the post and then forget about it. :P
Things have been really busy, but I still want to get around to re-writing the server to be a bit more stable and reliable.. I know it has its problems.
HOWEVER, if someone is interested in beating me to it and writing this server yourself, I'm happy to offer (C#) source code and help with any problems you have.
Essentially all the program has to do is connect a TCP socket to a cetian IP address which constantly streams over slightly modified NMEA sentences. NMEA is the format that almost every GPS receiver out there works, and I have documentation and code you can use to decode it.. it's not hard. After that you just have to maintain a list of bus locations you've decoded from the NMEA stream and be ready to hand out XML to anybody that makes a proper HTTP request.
That's reasonably easy, right? Or have I just been a programming geek for too long?