Why are you reading a old documentation (related to VMware VirtualCenter 1.2).
Read the VC 4.0 documentation (http://www.vmware.com/support/pubs/vs_pages/vsp_pubs_esx40_vc40.html).
VM and VM configuration file must be on a shared storage to use VMotion.
Andre
Andrew | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro