Wow... that is very good news! I fact I remember very well when there was an big effort to do this a few years back... well better late then never
Their idea to release the general assets and the code (under good licenses I would say) but not release the world data and story data seems like a wise way of running a commercial but open-source MMORPG... something other developers should think about too.
I am tempted to subscribe once they have a Linux version, even though I am not such a big MMORPG fan... when I tried the demo a few years back it seemed to have a rather nice art direction and a interesting story though.
Argg... now I am actually a bit annoyed that I am right now with a very bad internet connection and thus can not check the stuff out until I am back in Germany in a few weeks.