iCloud status icon already exists?
I believe that icon already exists. On my iPad last night at about 3am, I plugged it into the charger but continued using it. After a few seconds, I was surprised to see an icon appear next to the Wifi/3G icon. It was a rotating circle made up of 2 arrows following each other. This icon does not appear in the documentation, that I can see, so I'm assuming that it is my iCloud backup status. A while later, the icon disappeared.