It seems anyone with a refrigerator magnet could partially access the apps and information from a locked iPad 2, if the user has a Smart Cover and uses the locking feature. It can also be accessed just by using the Smart Cover itself. reported that the device could be accessed by following these steps:

1) Lock a password protected iPad 2

2) Hold down power button until iPad 2 reaches turn off slider

3) Close Smart Cover

4) Open Smart Cover

5) Click cancel on the bottom of the screen

This video, posted on Youtube, shows how the hack can be done: