Quickly Cut, Copy, Paste Entire Paragraphs
It’s well documented that when editing text on the iPhone you can double-tap to quickly select a word for copy and paste. But there’s an undocumented feature that also lets you quickly select an entire paragraph. Quadruple-tapping on any editable text highlights the entire paragraph, not just the single word. It might take a little practice to get it just right, but after only a couple tries it becomes much faster than double-tap-dragging to select a block of text. This feature only works when editing text, so don’t expect it to work while in Safari or other apps.
[via Mac OS X Hints]