Plex and XBMC would be ideal candidates for this API, each user could easily maintain their own pointer to the data set, and their synchronisation would be faster and more efficient than it is right now.

There's also a provision with the API (for personal use, so far) which turns a filename (and metadata, if you have it) into a JSON hash (or msgpack, of course) of the episode, show and season, etc.

This is also a potential avenue for being more widely made available.