Some of you iPhone users have been complaining about the period key being banished to the numbers and symbols keyboard layout. Well quit your whining, here's a quick and easy way to get around that. All you have to do is press and hold the numbers key, and without lifting your finger slide it over to the period (or any other punctuation mark) and let go. Ba-da-bing you've got yourself a period and the keyboard has automatically switched back to letters again.
Pogue's Awesome iPhone Period-Typing Shortcut [Missing Manuals]