I was just made aware of a new KB  article released by VMware regarding deleting large files on NFS server  and starting with ESX(i) 4.1u2, there is a new parameter that has been  introduced to allow for a longer delay for deleting files - http://kb.vmware.com/kb/1035332

This  may help permanently solve the problem around the issues users have  seen when deleting old VMs from ghettoVCBg2. I would be interested to see  for those of you still having problems with deleting files on NFS system  if this resolves the issue.