This isn't absolutely new and fresh, in fact it's sooooo last month ago, but I just noticed it. Here's the scoop from 3pointD.com: Rogue Second Life Server Goes Open Source.
While Prokofy Neva, Tony Walsh and others wonder what will happen to Second Life real estate investments once it’s possible to run your own open-source server (i.e., create your own virtual land), someone has gone ahead and done just that. This thread over at the libsecondlife forums describes a Second Life server built by a user, a single sim that can be accessed using the standard client software. As near as I can figure, the server was built by examining the client code (and/or reverse-engineering it) along with the information that is passed between client and server in order to get an idea of what the server code would need to look like. What’s more, an early version of the server code has already been made available as an open-source project. While this doesn’t mean that people can immediately set about creating the distributed metaverse that 3pointD often likes to contemplate (questions such as where everyone’s assets would reside in such a place remain to be answered), it is a step toward a virtual world, solar system, galaxy or universe free from centralized corporate control, one that looks more like the World Wide Web of individually controlled sites than it does a contiguous grid such as exists in Second Life.
This is more like civilization springing up in South America the same time as in ancient Sumeria, but the potential is there: once they "discover" each other, their economies and societies can intermingle. Evangelical warrior/explorers take note.
A more fun (and realistic) intermingling would occur if World of Warcraft were to suddenly open up a Stargate-like portal into Second Life. Would SL's warriors turn out to be girlie-men, or would they successfully defend us? If so, would that change their status in SL society from annoying griefers to warlords over all? Maybe I'd better create a second avatar and learn more about Gor... ;-)