Convert plain twitter urls, usernames, hashtags into clickable hyperlinks

Twitterify

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

#Thanks: http://www.snipe.net/2009/09/php-twitter-clickable-links/