After the lock screen problems with IOS6 where you could bypass the lock screen using the emergency call function, now IOS7 has a lock screen problem all it's own.
With IOS7 you can bypass the lock screen and access, transfer, view, email, tweet and facebook all the pictures on the phone. From the photo app you can access the contacts including their phone numbers and email addresses. You can also send out career-ending tweets or facebook posts. You can turn on Air-Drop and "drop" all their pictures to another phone if you think of turning it on prior to unlocking the phone!
Videos online show the procedure but don't readily give an idea of how to reproduce it because timing is everything. Here's the HOW:
1) Push the home button to wake up the phone if it's turned off.
2) Slide the photo icon up from the bottom of the screen (this will activate the camera app if they phone user end-tasked it previously
3) Push the home button to go back to the locked home screen
4) Flick the bottom panel upward
5) Click calculator (calculator app opens)
6) Push the top button for about 5 seconds until the phone presents you with the "Slide to power off" message and more importantly the "Cancel" button at the bottom of the screen
*** Do these two things as one step and try to get the timing right ***
7) Click cancel - push the home button twice (the push of the home button must happen about 1/2 of a second after the push of the cancel button... and the second click of the home button is about 1/2 second after the first home button click. The way I do it is say out-loud Click-Click clicking the button with each verbal cue)
8) You can scroll through open apps but the only app that lets you in is the calculator and apps available through the home-slide function
If you have an iPhone with IOS7 I'd recommend keeping it with you physically. If you do have to leave it somewhere you will need to edit your settings and turn off access to the control panel in the lock screen. (this option allows you to still use the control panel in unlocked mode) And of course, watch for an OS update and install it asap when it's available!