You could snapshot them all to get an image of a certain time by using a script, e.g. powershell.
To do so, you'ld probably have to pause all of the VM's first at the time u wish to snapshot.
If you dont mind the images being 10-20mins difference, then you wont need to pause them first.
Get-vm | new-snapshot -Name 'name of snapshot' -description 'description'
I think the answer you are looking for will be located in the following http://communities.vmware.com/message/1596564. You will need to create a file with the server names in and us that file with the script from the post.
I hope that helps and if it does then please leave me some points
Yepper - thx that was it.