Large setups would ideally got monitoring setup that would help.... i agree with you, on setups where we don't have proper setup to track host<>guest tie-up then it would be nightmare for admin folks.. I see that vmware tools if installed would be a handy candidate in these situations... check out this link:
http://www.virtuallyghetto.com/2011/01/how-to-extract-host-information-from.html