A new social 3D space Kaneva is launching soon, but apparently they just opened their doors for a public beta and guess who has sneaked (snuk?) in. In a nutshell, it's a rather good-looking MySpace-like social networking site in 3D that lets its users to customize rooms with stuff (photos, video and music). With its limited functionality, it's no Second Life killer, and it also suffers from some, in my opinion, unfortunate interface decisions, although the MySpace crowd probably won't care.
No Mac support yet, and a pretty hefty PC upload. It's a rather claustrophobic world since there's no "outside" -- you jump from one room to another much like you visit websites. Apparent advertising opportunities so far: video and audio channels, branded items in the Kaneva stores, textures, branded avatars, and sponsored events. Yeah, and you can advertise on the 2D site through AdSense. More details in the comments to the SlideShare deck. Also see Greg Verdino's (Digitas) take.
Funny, I have a friend in Bulgaria whose last name is Kaneva.