Allows to detect mentions, hashtags and links in a tweet and create links.

twitterify.php

<?php

function twitterify($str) {
  	$str = preg_replace("#(^|[\n ])([\w]+?://[\w]+[^ \"\n\r\t< ]*)#", "\\1<a href=\"\\2\" target=\"_blank\">\\2</a>", $str);
	$str = preg_replace("#(^|[\n ])((www|ftp)\.[^ \"\t\n\r< ]*)#", "\\1<a href=\"http://\\2\" target=\"_blank\">\\2</a>", $str);
	$str = preg_replace("/@(\w+)/", "<a href=\"http://www.twitter.com/\\1\" target=\"_blank\">@\\1</a>", $str);
	$str = preg_replace("/#(\w+)/", "<a href=\"http://twitter.com/search?q=\\1\" target=\"_blank\">#\\1</a>", $str);
	return $str;
}

?>