vComm solutions have released a video showing some of the features and architecture of their Aula enterprise training and meeting environment for OpenSim and SL. 

For a higher resolution look - go here
I was lucky enough to get involved in helping make the video, and it suddenly occurred to me that just in getting together to do that, we were demonstrating the power of immersive environments for virtual team working - there were three of us in different parts of the world, and yet we were able to complete the filming and work well together as a team.  This stuff works, and for anyone wanting a ready-to-run way to get started, Aula looks like it might be a good contender.

Update:  I should make it clear that this video was shot in Second Life.  The architecture and facilities offered in OpenSim will apparently be very close if not identical although speech gestures are not yet implemented.  When I get to see the OpenSim solution I'll provide more details.