Press an hold down the “home” button on the face of your iPhone and then click the on/off button at the top. The screen will flash white.
Now switch to your Photos application, your screen shot will be in the “camera roll”. You can do all the usual things you can do with Photos: Sync back to iPhoto, email out your images etc.
The iPhone 2 screen shot is a 320 pixel wide x 480 pixel tall jpeg.
Caption: Full size example screen shot of the vertical Gmail keyboard in Safari.