This bug easily exposes your iPad 2 to undesired access, here are the steps a perpetrator would have to go through:
• Have a lock passcode enabled iPad 2
• Hold down power button until it reaches the shutoff slider screen
• Close Smart Cover
• Open Smart Cover
• Then just click cancel
To prevent this access temporarily, you can disable the SmartCover unlocking ability in the iPad 2 settings menu under the General tab. Apple will likely fix this flaw in iOS 5.1, it may not be fixed for the release of iTunes Match though.