Hopefully the question makes sense. I see that it is possible to connect to the console of a VM through the VI Client when another user is already connected and share the same view of the active session. Is there any way to limit the number of connections to only one at a time?
You are correct. This is a per VM setting. If you set it correctly in the template, then any new ones would follow suit.
To add it to any existing VM's, you'd have to power them down, and make the change.
With a little fancy scripting, you should be able to append the setting to all of the .vmx files. That way, if you were in the middle of a maintenance window, where you could power down VM's, you could push the changes to each of the .vmx files.
Co-Author of VMware ESX Essentials in the Virtual Data Center
(ISBN:1420070274) from Auerbach