Useful blog post over on the Virtualisation blog, which covers unattended installs of WS2008 and Hyper-V, so you're ready to rock as soon as the install is complete.  Check it out here: http://blogs.technet.com/virtualization/archive/2008/05/07/unattended-installation-of-windows-server-2008-with-hyper-v-rc0.aspx

This is a nice follow-up to the post I wrote the other day, around applying a Ghost/ImageX image to a machine where you need to apply the Bcdedit /set hypervisorlaunchtype auto command upon completion of imaging.  Using an unattended install, this shouldn't be required.