initial feedback at Virgin's Help & Support Forums looks promising, with reports of improvements in performance and SD picture quality, along of course with the other features previously mentioned, including one which wasn't previously mentioned - the start and end times of programmes are now displayed in the EPG.
The software version is SW: 15.2.RC8-VMC-2-C00. The Flash Player version is 15-2-mr/2011.10.26-1905, while the user interface version is HDUI: compass-2/2011.10.28-1830
Functionality for Multi room streaming is in the update, but this thread indicates that the actual streaming is being blocked by broadcaster restrictions.
V6 update being rolled out - There's a new update being rolled out to V6 boxes to address some of the bugs. If you have the update your firmware level will be 220.127.116.11.RC6-VMB-11-C68 ...