One way to select an entire paragraph on the iPhone is to touch and hold to select a word and then drag the grab points to select the paragraph.
Folks at MacOSXHints have stumbled on an easier and quicker way to select an entire paragraph while editing text on the iPhone.
The tip discovered by MacOSXHints doesn’t seem to be documented even on Apple’s website. Tomaria of MacOSXHints writes:
I discovered that you can select an entire paragraph of text by quadruple-tapping on it when entering text in the iPhone. For instance, when replying to an email, you can quadruple-tap on paragraphs in the quoted reply, then cut them.
You have to do it pretty quickly, and take care not to move your finger too much between taps. Try it a few times, though, and you'll get the hang of it.
It is always nice to discover something undocumented so kudos to folks at MacOSXHints. Let us know in the comments if you found this iPhone tip useful.