One of the great features in OCS 2007 R2 is the support for HD video for peer to peer calls. This is still not supported in conferences, however you can utilize VGA and HD Cameras in video calls between users. There are a couple of important things to know about this to get it working.
You will notice in the Front End settings for the pool you can specify a maximum video quality:
This setting will specify the maximum video quality for the pool, however you will need to provide client side policies to enable higher quality video.
If you wish to utilize VGA or HD720p video between two endpoints you will need to ensure the below registry entry is present on both of the clients.
Windows Registry Editor Version 5.00
This will allow the two users to send and receive HD video, by default this is not enabled.
You will want to make sure you take bandwidth and PC capabilities into consideration when enabling this feature because video can be intense on the client desktop as well as a bandwidth killer as you can see in the first screenshot with the estimated amount of bandwidth required to send that video stream.
You can find more information about the client registry setting here: http://office.microsoft.com/en-us/help/HA102362191033.aspx
You can find more information about the OCS R2 HD Video enhancements here: http://technet.microsoft.com/en-us/magazine/2009.03.ocsr2.aspx?pr=blog
At this time there are no HD Video endpoints certified for OCS but by the end of this year Tandberg and Microsoft should have desktop USB devices capable of HD720p video with OCS.