Linden Lab, developers of the popular 3D platform "Second Life" started to think about an open standard for interconnecting virtual worlds. The motivation behind this is to make Second Life more scalable but also to allow connection of other grids not hosted by Linden Lab. The process of defining components and protocols is supposed to be handled completely in the open with community participation. When finished the protocol documentation is supposed to be submitted to standard committees such as IETC, W3C etc. The discussion has already started on the Second Life wiki and you can also find a first architecture proposal by Linden Lab.

http://wiki.secondlife.com/wiki/Architecture_Working_Group