Undo and redo typing quickly: Shake it, baby!
Simply shake the iPhone or iPod touch to undo the text you just entered. A pop-up appears, allowing you to confirm the action by hitting the Undo Typing button, or cancel it. If you decide you didn’t really want to undo the typing, shake the device again. This time, the pop-up will let you Redo Typing.
This feature only works with text you just entered in the current data field. For example, if you create a note with the phrase “Pick up hardware for door” and close the note, that text cannot be deleted with the shake feature if you open the note again. Also, if you’ve filled in the To field in an e-mail message, and move to the Subject field, you can’t go back and use the shake feature to delete the address. Fortunately, there are other ways to delete text that cannot be shaken away.