Continued building a system for transferring the complete internal states of our dimensions from the server to the client. However, Steven suggested that clients only need minimal data to operate properly, as opposed to the server. My motivation for this more complicated system was the concern that minimal information wouldn't be enough. I'm going to commit my progress, then tear it down and write a much simpler version.
DimDoors
Dimensional Doors for Minecraft Adds several items that allow the player to move between and create dimensions
see the MC forum topic for details