This is a 31 minute long recording of Adam Ramonas (Adam Nash in RL) wonderful sound installation in Second Life. The sound was recorded at the presentaion of the installation in the ending part of the Dorkbot/SL third meeting on the 17th june 2007. There is plenty of avatars moving around in the sound installation.
You find Adams site here:
The blog announcement for the 3rd Dorkbot/SL meeting: