A bug has been found in iOS 7 that allows a an attacker with physical control over a lost or stolen iPhone to get around Activation Lock and gain access to the device. Unfortunately, the method for circumventing Activation Lock has been made public. However, the bypass process requires the attacker have access to an unlocked device, and be able to access the device after a reboot, so it can be thwarted by simply having a Passcode enabled (either by itself or as part of Touch ID).
Hopefully Apple is already working on a fix and iOS 7.1.1 or a similar update will patch it.
Nick Arnott contributed to this story.