I tried following the Instant Upgrade directions for changing serving permissions/chmod'ing files and directories to 777, and the server wouldn't let me into my site. So I had to change all the permissions back.
I then ran the upgrade from within the control panel to see what would happen even without the server permissions changed. It gave back the message that it upgraded successfully. However, I have no way of knowing if this is true since I was using the most current WP anyway.
So, how do I know if the Instant Upgrade is working even without the relevant server permission?