Even if Sun was brought by Oracle, wonderland seems to live on albeit with a slightly different name
http://www.openwonderland.org/

Open Wonderland is a 100% Java open source toolkit for creating collaborative 3D virtual worlds. Within those worlds, users can communicate with high-fidelity, immersive audio, share live desktop applications, and collaborate in an education, business, or government context. Wonderland is completely extensible; developers and graphic artists can extend its functionality to create entirely new worlds and add new features to existing world.

Of course open cobalt http://www.opencobalt.org/ is still going, and stereo 3D has been added, http://nsuslovi.blogspot.com/2010/04/stereo-3d-filter-in-open-cobalt.html

UPDATE: Another peer to peer metaverse is http://www.solipsis.org