iTunes 11 AppleScript bug
iTunes 11 breaks the AppleScript command to shuffle a playlist. The value of shuffle can still be read with get, it just can't be set.
Update: song repeat is broken in the same way.
Update 2: shuffle and song repeat will only return a value of false and off, respectively. Thus, in addition to being unable to change these values for a playlist, a script cannot detect the actual state of these settings.