If your using an Android phone it is possible, but can be some what of an issue if you have not rooted (modify it by changing the standard settings) it.
You would think it might be easy to just capture an image of what exactly is on your screen but it is not. You can use Google’s Android developer kit but even that is not simple (unless your committed to your tech).
However on the Samsung Galaxy S II, you can take a picture of exactly what is on your home screen at any time, by simply pressing and holding the power and home key at the same time.
A capture sound is made and the image is then saved to your gallery, for you to do what you like with.
This is an excellent feature and will make it easier than ever for Samsung Galaxy S II users to share on screen content.
So to take a screen capture on the Galaxy S II:
Press and hold the power button at the same time as the home button.
View the screen capture image in your gallery.