Dont mean to ring back up the multiserver multi map topic. But it seems to me that it could be easily done with transition maps. the concept is if your going to move from one map to another there is an intermediate map that you must cross. This allows for the server to do what ever it needs to do ahead of time to make the required connections to make the operations as smooth as possible.

Another way of looking at it is .hack sign ( for those who dont know its a really kool anime that needs to be seen) like basically have telepotation points to different servers. even though this would ruin the real world feel of the game but the same scenarios could be used.

Finally, even though you dont want to have to think about it now it should still be put on the to do list for the game. for example it can be a feautre used in lans where you can generally garauntee low pings between servers. Or it could be enabled on servers in the same location to allow for different scenarios to be played out.