I just committed xmpp backend code.
The backend code can:
If you don't specify a database, it will ignore your laziness to setup a proper database, and go ahead storing files, if you don't specify a location where to store files, it will just create noise on the terminal.
The database schema is part of the commit, nothing really fancy, a basic port of the logsql schema to postgres with some candy, using enums for connection_types and connection_transport to save some bytes on the long run.
Unfortunately enums require postgres >= 8.3, but …
As I'm a great fan of postgresql_autodoc, here is a picture of the schema:

click for large version
Running sensors (anonymously) is free for all, running a backend requires elevated priviliges, if you want to run a backend, contact me.
Hello Markus, I am interested in running my own backend, any guidelines?