Great shortcut for periods and commas!
Basically, you can type a period with ease if you simply press the ‘.?123’ key, then keep your finger on the screen and just slide it up and over a bit to the period when the numeric keypad appears. Amazingly, this key reacts as soon as your finger touches it (no lifting required), and the numeric keypad will automatically disappear when it does, leaving you right back where you started with the normal keyboard active—and with a period in your document! And instead of multiple taps, it took but one.
It works for the comma as well, you just change the angle of the "slide".
Original post is here: http://missingmanuals.com/poguesawesome_iphone_typingshortcut.csp
MacBook Pro 15" Mac OS X (10.4.10)