Again please forgive me for using UML class diagram tools for designing the DB.
Here you can read more and get into details. I will try to finish the implementation until monday leaving the current interface unharmed.
Xesam as described by their page is:
short for eXtEnsible Search And Metadata and is an umbrella project with the purpose of providing unified APIs and specs for desktop search- and metadata services. We are collaborating with several projects such as Tracker, Strigi, Beagle, Pinot, Recoll, and Nepomuk-KDE.
This will allow us to use annotation as tags, bookmarks,and custom comments. Also its a good preparation for a optional Tracker backend as well as co-operation with other FLOSS Projects involved with RDF semantics while still being a project of our own. I am worried however how it is going to scale. But I guess nothing that some indexing and tweaking wont fix.