I was testing some of the scripts I have posted on this site with vmware server and they do work. A client I am currently working at is using Virtual Center for all of their VM management, this to avoid giving users access to the console and also to have a central place for the VI management instead of replicating shell scripts to each ESX.
Their VM backup solution exists out of file-level backup/restore done by a backup agent installed within the VM, but in addition they also wanted to have a backup of the VM's vmdk and their configuration files for quick recovery. Another requirement was that the backed up vmdk files should be located on cheap media (so not on a SAN).
Now while there are several third-party tools on the market that can do this for you, I have choosen for a far cheaper solution and purchased one VC Agent license for vmware server and clone the VM's to Vmware Server. Not only it is cheaper you also avoid introducing "another" product ... !!
Check out the download section, for examples on how to clone a VM. Also cold-migrations (part of the vmUtil.vbs script) do work as well.