If you read portuguese, you can read our free tutorials about Unity (multiplayer included) at:
http://www.dmu.com
There are some lessons about how to import independent avatares, serialized, from the web inside a multiplayer game (metaverse?).
Many real demos, videos, code etc.
If you don’t read portuguese may be you can use Google translation.
Explaining better the architecture presented in the tutorials: a game would be like a browser. The player will give the internet address of an avatar when entering in the game (login). The game creator (the company) can sell a software for the easy creation of avatares for their games. Or independent producers can make and sell avatares.
What do you thik about this architecture? Is it genial or an idiot thing?
Do you know any game that works using this idea? I don’t know but, maybe it exists…
The "sculpy"s of Second Life is something like. But we can not create an sell games using SL…