Have been thinking about this, too. I will try to extract the TMC databases of event and location codes from my car's navigation DVD.

Our hacking friends on Windows Mobile have done something very similar over the last few months: TMC R&D: Get TMC from the FM radio of your device . This might give us a LOT of information on what to do.

Interesting overview on an engineering company website here in Switzerland.

And some more from SourceForge