I came across the Yugma web collaboration application a while back but haven’t had time to test it out. Chris Nadeau has been using it and says that it compares favourably with applications like Webex and Vyew. Yugma requires a download (thin client) which may limit its use for those behind the firewall.
What really interests me about Yugma is that it offers free tele-conferencing, something not available on the free/low-cost Vyew application and much too expensive on Webex. Yugma may have found the sweet-spot for free web conferencing.