This is a good read.
They are FINALY bringing what they call "Vmotion Storage" where you can change the datastore that your VM uses without having to shut it down and do a migrate.. Yippie!
Also new HA features... Read the snippit from the above link.
Last he end with a “High Availability” section. Detailing the “record the execution” feature now available experimentally in Workstation 6 where real-time activity is recorded and logged to disk, and replayed at will for application debugging purposes. This new feature has been dubbed “Continious Available” for ESX. In this case you have a primary and second VM on two different ESX hosts. The primary VM on the primary ESX host is continuelly sending the record data to the other VM - not to a log file. The two VMs held in synch. In the demo, when Mendal clicked the start menu you saw this happen on two VMs on two different ESX hosts at the SAME time! See it like two VMs mirrored. Next the pulled power cords out the back of the primary ESX host - and the other VM just kept on running. It was an Exchange server with 100+ of emulated user activity… So this is great - what everyone has been asking HA to do, which currently does do. Sounds great huh? But just remember if the primary VM has a BSOD - so will its mirror…