Converts a plain old tweet to a fancy one with links all over the place.

linkify.php

<?php

/**
 * Adds links to tweets
 *
 * @param string $tweet The raw tweet
 * @return string The tweet with links
 */
function linkify($tweet)
{
	// Link to URLs
	$tweet = preg_replace('/((mailto\:|(news|(ht|f)tp(s?))\:\/\/){1}\S+)/', '<a href="$1">$1</a>', $tweet);
	
	// Link to users
	$tweet = preg_replace('/@([a-z0-9_]+)(\s|$)/i', '<a href="http://twitter.com/$1">@$1</a>', $tweet);
	
	// Link to hash tags
	$tweet = preg_replace('/(^|\s)#([^\s]+)/', '$1<a href="http://twitter.com/search?q=%23$2">#$2</a>', $tweet);
	
	// Return the tweet with links
	return $tweet;
}