WatchedList - service to automatically save/restore watched state

I know this topic has been discussed by quite a few Threads and addons.
As there is no working solution available for Frodo (at least I found none) I hope my addon can fill the gap:

service.watchedlist
script that saves and restores the watched state of movies and tv episodes.
Project page with zip-download:
http://code.google.com/p/xbmc-addon-serv...loads/list
Wiki-Page with installation manual:
http://code.google.com/p/xbmc-addon-serv...dListHowTo

Advantages

1. only clean access of XBMC database with JSON-RPC. No "dirty" manual database opening or reading xml files.
2. starts as a service in autostart and repeats periodically
3. automatic backup of addon database
4. no user interaction needed
5. addon database (SQLite) is easy to edit, in case wrong watched states are stored
   

Screenshots:
the script only communicates with notifications. More pictures in the wiki.


Participation
This addon was only tested under Frodo 12.1 on two clients. Feedback would be great:
http://code.google.com/p/xbmc-addon-serv...ssues/list
If this works I plan to add it to the official repository.