You can find the update here:
Upgrading from Beta or RC0 or RC1:
If you have any VMs with a saved state be sure to remove that saved state prior to upgrading the Host.
- This is any VM with a saved memory state
- A VM currently in “Saved”
- A VM that had an online snapshot taken – while the VM was running
- Delete the online snapshot (from the Hyper-V Manager), power down the VM, wait for the snapshot merge process to complete.
Cleanly shutdown all VMs prior to upgrade of the Host
- Not cleanly shutting down a VM will cause the Host to place the VM into a saved state by default, thus creating the risky condition above.
You can patch the WS08 guests prior to upgrading the Host
- Just power them down instead of re-booting
Be sure to upgrade the Integration Services in all children
- Simply open a console connection to the VM, login, choose Actions -> insert Integration Services disk and allow the upgrade to happen.
- If the new device wizard appears in the VM, it will prevent the Integration Services from being upgraded
- Just cancel the new device wizard within the VM
Using SCVMM 2008 Beta:
To this moment the VMM team has reported no issues with the Hyper-V RTM when the SCVMM Hyper-V RC1 patch has been installed. (your mileage my vary)
To obtain the SCVMM Beta Hyper-V RC1 Compatibility patch:
When installing the patch, have some patience – it will cause strange things to happen until you push new agents onto each managed host (after the host is raised to Hyper-V RC1) and the Hyper-V RC1 patch must be applied to the SCVMM Server (in addition to the SCVMM patch).