Although not as architecturally sophisticated as the effort described here, I've been running several prototype plugins on Centrafuse3 that provide live traffic, traffic cameras, RSS feeds, weather, Google calendar, location-aware search, personal notes and assorted streamng media. All of the information is derived from web-based APIs of one form or another.
If your effort is to try and aggregate information and resources relevant to a carPC users, and present it as an RSS/REST/Web Service/XMLRPC feed....its already being done. Almost all of Google, Yahoo and Microsoft's services are available as APIs. Trafficland, BeattheTraffic.com and others provide real-time traffic updates, EVERYBODY has an RSS feed nowadays. What's the difference between writing a plugin that accesses your service and writing one to access Yahoo?
What is the value added?