Aurora-Sim
So with everything that's been happening with me working on virtual environments, I return to Aurora-Sim.
Several months ago, the group working on Aurora-Sim were busy redeveloping the OpenSim server software in a way that works closely with the OpenSim/SecondLife and other third party clients. At the time they didn't have much of what I was looking for especially in extensibility. But going to the site again today and reading up and visiting their IRC chat via their website, I was able to discover that modules can be programmed and added to the server.
Everyone on the team is quite busy with the software or life to really focus on one thing, but I'm sure someone with knowledge of C# and a bit of help from the IRC could create a wrap for Python or Java for even better extensibility.
At least what I'd love to see added is some sort of VNC viewer, and from what people in the chat were telling me, it would probably work best added to the MOAP (Media on a Prim) functionality.
This group seems to have the same dream RealXtend did in the early days of Tiaga and Naali, but have kept with it and are making something that will work well for education and business virtual models.