Google’s Lively.com - 3D virtual experience
Google has just released its own virtual world: Lively. Lively is available through a browser plugin for Firefox and Internet Explorer. It is Windows only for now. Lively does not feature one coherent world like Second Life but splits worlds up into different rooms. Lively was originally developed as a 20% project my Niniane Wang.
Lively is still very much a "beta"–actually a Google Labs project–so you shouldn’t expect much from it. What you will find is a chat room with some cute 3D graphics that feels a lot like what you’d expect if Second Life and Zwinky had a child.