Vivox voice services are used in Second Life already, and give high quality spatialised sound for such environments.  See http://www.vivox.com. A "Vivox Voice Gadget" is available to add voice facilities into a Google Wave. See:

• http://wave-samples-gallery.appspot.com/about_app?app_id=133002
• http://www.wextensions.com/2010/03/31/wave-gadget-vivox-voice/#more-1023

Introductory  Video

• http://www.youtube.com/watch?v=01hvGFag_uM

Gadget URL
To install, please edit your wave, and add a gadget.  Give this URL:

• http://vir5ag.vivox.com/dave/google/GoogleWaveGadget.xml