best example is the 3d chat demo for ANET, it does exactly what you want already but limited to 4 people, upgrade if you want more... http://www.anet-plugin.com/downloads_eng.htm

team INOV:
CURRENT PROJECTS: http://www.youtube.com/user/teamINOV?feature=mhee
FOLLOW US on twitter: http://twitter.com/team_iNoV
check our blog: http://scionwars.blog.com/
shaders: http://shadec.project-havoc.com/
networking: http://www.anet-plugin.com/