I'm looking for any material on seamless MMO servers! I do have a few articles in the "Massively Multiplayer Game Development" books and "Game Programming Gems 5." Has anyone experience on that topic or knows articles about that? 

I'm interested in "high-level views" as well as implementations. This might become the topic of my master thesis and I would like to find out how hard it is to write such a system, before I actually start the thesis. Right now I haven't decided which language to use, I'm thinking about Java or Scala. Erlang could be a choice, but I've never worked with that.

Note: Basic requirement would be movement. Any other gamesystems are optional and give "bonus credit."

Now for what I mean with "seamless server": I want so set up a server cluster where every node controls some part of the game world, with static boundaries. Players can now move from one end of the world to the other without switching an instance or hitting some "teleporter". I think WoW does that. In my back-end however the player transitions from one server to the next.