There have been reports (and here) of iOS 5.1 containing a camera bypass tied to the new camera shortcut on the lock screen. The people who have reported this are sadly confused about the security timeout enforced by iOS’s Require Passcode setting (Settings > General > Passcode Lock > Require Passcode). If your Require Passcode setting is set to anything other than Immediately, then your device (and the camera roll from the camera shortcut) will be accessible for the entire duration of time specified (ie. 1 minute or 5 minutes).
As always, the best setting for Require Passcode is Immediately. That way you know that when you lock your device, it is actually locked, and will prevent someone from gaining access to it without the passcode within the minutes following the ‘lock’.
Sadly people seem all too eager to rush and report on iOS vulns before actually verifying them.
TDLR; There is no lock screen bypass in iOS 5.1 using the new camera shortcut. They were wrong.