The current version of their service as deployed is 5.0
The last open source release is 4.5 as of the beginning of 2008... it is only available in a semi-working state as a complete VMware image, I can't get any of their installs to work after spending a few man-weeks on it. The VMware image is based on CentOS, which I'm totally unfamiliar with, customizing it was a nightmare, at best. Because it's an OS I'm unfamiliar with, I have no way of knowing what other things it is doing in the background.
I GIVE UP.
Learn from my errors, Save your time and effort, find some alternative to do your video conferencing.
Oh... and I'm not alone...
Read the comment by David Strickland at http://ostatic.com/dimdim