Can across a new bit of software this morning (Thanks to Mike Laverick of www.rtfm-ed.co.uk for putting me on to it)
http://www.vmts.net/VMTSPatchManager.htm
Installed it in my test lab this morning on the Virtual Center server,
It pulls all the host details from VC, just needs the username and passwords.
ESX needs to be in maintenance mode.
Its really simple to use, planning to install it on a live VM next week then schedule some down time for the live ESX servers (Vmotioning the VM's off first 
)
Come on VMware make this part of Virtual Center....
I'm also looking into this software right now. Looks good so far.
"Come on VMware make this part of Virtual Center..."
Patience