While a few tech sites have claimed success in using the hack, I've yet to replicate it entirely. Using my iPhone 4, the screen just locks out again after I complete the last step.
"For prank your friends…for a magic show…use it as you want, at your own risk," reads the YouTube video's description. "But please, do not use this trick to do evil!!!"
And honestly, who doesn't love a good security-breach magic show? If you do manage to bypass the lock screen, you can apparently make calls, access voicemails, and even look at recent photos. But don't freak out entirely: the perpetrator can't change your lock screen code, or even access much beyond the calls and photos. No word from Apple yet, but I'm assuming a fix is forthcoming.
UPDATE: An Apple representative has contact All Things D, and the company is said to be addressing the problem. “Apple takes user security very seriously," said Apple's Trudy Muller. "We are aware of this issue, and will deliver a fix in a future software update."