Can I view what app data has not been uploaded to iCloud?
Instead of going to Preferences -> General -> Usage, go to Preferences -> iCloud -> Storage &amp; Backup -> Manage Storage.

This screen will list your devices and by selecting the current device (like your iPhone if you're looking at it on your iPhone) you can see the list of applications that saves data to the backup. Here you can see the backup size per app and you can also disable/enable them individually.
To modify the settings for your other devices you need to go to the same screen on them.