One of the new features included in Android 4.2 is the addition of widgets to the lock screen. These widgets (a total of five currently available) provide a preview of your inbox, the clock, messages, calendar, or a shortcut to your camera and a widget to quickly identify a song.
You'll, of course, need to be running Android 4.2 in order to have access to the widgets. That is, until developers figure out how to get it working on other Android versions, if they haven't already.
When you first wake the screen on your Android device, you'll see a white line on either side of the screen. I wasn't fast enough to get a screenshot of the lines flashing on the screen shortly after you wake the device. They're there, then they're not. The lines indicate there's more information on either side of the main screen.
Placing your finger on the right edge of the screen and swiping to the left will take you into the Camera app.
Going from the opposite edge and swiping to the right will allow you to add widgets or allow you to view any widgets you've already added.
To add a widget to your lock screen, slide the screen from left-to-right until you get to the card with a plus sign on it. Tapping the plus sign will reveal list of available widgets. Select any widget you'd like to add to your home screen by tapping it.
Should you want to rearrange the widgets, you can tap and hold, then drag the widget to the spot you'd prefer. If you want to remove one, just drag it to the Remove text at the top of the screen. The widget will turn red once you're OK to lift your finger.
The Digital Clock widget is the only widget (as far as I have been able to tell) that's adjustable. You can increase the size of the widget, revealing any world clocks you've added to the Clock app below the current time.
The lock screen widgets are a great idea, but they can't help but raise some privacy concerns. Even if you have to unlock your device with a pattern or PIN, some information is still revealed by the Gmail or Messaging widgets. Keep your privacy in mind when enabling either of those widgets.