I was fiddling with my iPhone 4S when I suddenly came across this handy feature to take a screen shot without any third party application.
This with would be an useful feature if you need to take the screen shot of a google map and you have no internet or other innovative uses.
To take a screen shot from your iDevice, press the button on top, and the home button simultaneously at any screen.. Bham.. you have your screen grabbed and saved to your photo gallery.
Go to the photo gallery and check it out. This has been introduced from firmware version 2.0 in all iDevices.