In the virtual server virtualization, it can be pretty similar. What we are seeing most people do is deploy the same type of environment in which they are installing a backup agent inside of the guest OS or inside the virtual machine itself. There are other instances in which people are using the server virtualization vendor tools; these tools complement the backup process. Some people are writing customized scripts; there's some that run on a Linux kernel. With others you can make calls directly to the server virtualization hypervisor itself, which helps with the backup process. Other people are backing up with snapshot.
There are lots of options, it's really just understanding what is best for your environment.
Check out the entire Virtual server backup FAQ