A couple weeks back, a major security flaw in the iPad 2 was discovered, one that allows anyone with a Smart Cover to bypass passcode lock security on an iPad 2 running iOS 5 (and possibly on older firmware as well).
Now a fix is on the way from Apple. Last night they released a beta version of the iOS 5.0.1 firmware update. 9to5Mac have tested and confirmed that this update fixes the passcode bypass security issue.
It appears that Apple has fixed the issue by not allowing the iPad 2 to go to sleep by way of the Smart Cover closing while on the power off menu.
We should see the iOS 5.0.1 update released within the next few weeks.