I have tried on three different Macs (two running Lion, one running ML), but I can't access 'manage devices' in iTunes. I have iCloud running everywhere, but no matter what I do I can't find 'manage devices' anywhere in my Store account settings.
I need to disassociate an iPad i sold from my iTunes ID, and the invisible Manage Devices section is driving me to distraction!
Mac OS X (10.6.8)
Did you have Automatic downloads enabled on that iPad?
It won't show up on your account unless you enabled it in iPad settings > Store.
It's not just automatic downloads that will associate a device to an Apple ID.
"When you turn on iTunes Match or Automatic Downloads, or when you download past purchases on an iOS device or computer, that device or computer becomes associated with your Apple ID. This article describes how to manage these associations." ...including how to remove the association. http://support.apple.com/kb/ht4627
Unable to Manage (iOS) Devices
