Even though the 1.5 version is not ready yet, I also have in mind the next release, 1.6, which will introduce a much needed DB rethinking. Currently the DB schema is very weak and inefficient, making it difficult to introduce new features and having lots of redundant data. Another effect of the “never thought this project would get that big” syndrome.
What I have currently in mind is this schema:
Comments welcome on the wiki page to keep things in one place.