I am using a cloud hosting provider, which uses dedicated servers. They let you "image a disk" and then cancel the server. To image the disk, they use software which is similar to Clonezilla (no name known). However, would there be any problems with doing this on a dedicated server which is hosting a domain controller (or a dedicated server running a hypervisor with a vm which is a DC), or on a server (either the physical or virtual childs), hosting VSS-aware applications?
If it's a lone domain controller (the only one in the forest) then you are usually OK to use cloning tools on it, provided the server is shut down at the time it's cloned.
The original server must be destroyed if the clone is ever brought online, however, as the two cannot co-exist. The cloned server will also only be valid for a short time, because domain clients have credentials which they use to talk to the domain and they silently update these credentials quite regularly. This means that if you bring your cloned DC online, and a client has updated it's credentials since the clone occurred, your client will no longer talk to your domain.
So lots of caveats. General advice is that unless your domain is unimportant (e.g. just being used for some development), don't clone DCs.
I've just done exactly this. We had a client on a physical hosted server running 2008 as a dc + exchange and I had to move it to another box where it was going to be virtualized. I used disk2vhd from sysinternals to do the p2v part. No real problems.
Windows licence - remember oem can't be moved, other licenses such as enterprise and datacenter are tied to the physical servers licence.
DC duplicate issues - so long as this is a migration and you are going to kill the old dc straight away then you shouldn't hit any problems
Drivers and reactivation - as always drivers can be an issue, though with 2008 this is pretty smooth in general.
Remember you can try this out beforehand to see what happens. Use disk2vhd to generate a vhd. Compress it and download it. Fire it up on your PC using virtual pc and see if it works. Remember to create an isolated network so theres no chance the vm can talk to the old server or others if you have any in your domain.