The guys over at JailbreakNation have made a shorter and clearer one, and have proved that videosdebarraquito's claim is true:
The good news is that the steps are many and unlikely to be executed by random attackers. The bad news is that this trick has been shared all over the Internet.
So, until Apple pushes out a new version of iOS and fixes the flaw, you might want to consider not leaving your locked iPhone unattended, especially around people you don't trust.
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