This script performs backups of virtual machines residing on *ESX(i)
3.5/4.0+* servers using methodology similar to VMware's VCB tool. The script
takes snapshots of live virtual machines, backs up the master VMDK(s) and then
upon completion, deletes the snapshot until the next backup. The only caveat is
that it utilizes resources available to the Service Console of the ESX server
running the backups as opposed to following the traditional method of offloading
virtual machine backups through a VCB proxy.

Script:
http://communities.vmware.com/docs/DOC-8760