Virtual Property - Business Models And Pitfalls

Another outstanding issue associated with virtual property is ownership. Who actually owns these objects, characters, and land after they are "purchased" from the company? Most EULAs state the game company owns the intellectual property in the objects and the players are merely purchasing a limited license. Still, this is changing with some companies, such as Linden Lab, experimenting with EULA provisions that grant limited ownership rights in user-created virtual property. In fact, the Bragg case was only possible because that particular world, Second Life, acknowledged some limited player rights in virtual land. There are also companies like Metaplace that are developing technology that allow users to build their own virtual worlds, literally creating the world with their own IP.

from The Metropolitan Corporate Counsel

see also Dan Miler's post