This the place for ideas of how the protocol can be utilized. Some of them are duplicated in concept.
Technically it is room (room is a term describing location on server) with number of triggers inside. Some of them may be activated by opening a door to some building, others - by loging in computer or by entering teleport. Activating a trigger leads to teleporting client to another server. Navigation cities play role of “visual DNS”. Visually it doesn't even have to be city in accustomed meaning. It may be forest or village or whatever it is. Physically navigation cities should be stored on special servers where people should register their servers. Just like plain DNS except there is 3D space instead namespace.
Personal character is a set of mesh, skeleton and animation written in standartized way so movements can be easily animated on client using standart script. Mesh, skeleton and animation are stored as global resolurces, they will accessible by everyone, but first user needs to register them. As many features of Kernel Panic project as a whole, this feature isn't implemented on client side, but is just one of declared server-side standarts.
Like personal characters, BSP map is implemented on server side. Meshes should be extracted from BSP and rendered separately. And geometry (for physics) of map should be sent as local resource(s) (possibly in different format than BSP). Sounds simple, hard to implement.
Now, this is about RPG, where real humans can get into monsters and NPC's. But still without human interaction levels should be interesting. This would make for example guards' chasing real problem for player (not just “I guess, it just seemed” replics and back to patroling). Playing NPC by humans gives an ability to gain some information using communication skills and just some realizm to game.
This should be implemented using additional logins for masters. It should probably look like screen splitted into several viewports from cameras. By clicking on one of them master would get into corresponding monster or NPC.