WHERE
On Google's Lively
On Just Leap In
On Meez
And the Meez Room.
On Vivaty
Sample Vivaty scene, as a Facebook application for Windows XP or Vista, and with IE browser only at the moment.
On IMVU
To IMVU's avatar homepage.
Embedding IMVU rooms loads as a complete page.
On Second Life
...
On OpenSim
...