Is there a way to determine when an iOS upgrade was installed? Is there any way within iOS, or via iTunes on a computer, to see the date when a particular iOS upgrade was installed on my device (iPhone/iPad)? Not the date the upgrade was released, but the date that it was actually installed.
If you have updated iOS through iTunes, you can look in your iTunes data folder, on a Windows machine that will be: 

C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates\

Then check out the timestamp on the iPhone..._Restore.ipsw file. That will be the date you upgraded (or downloaded) our latest iOS update.

If you updated it directly on the device, I don't think it is possible to retrieve its date.