function twitterize($raw_text) {
	$output = $raw_text;
 
	// parse urls
	$pattern = '/([A-Za-z]+:\/\/[A-Za-z0-9-_]+\.[A-Za-z0-9-_:%&\?\/.=]+)/i';
	$replacement = '<a href="${1}" rel="nofollow">${1}</a>';
	$output = preg_replace($pattern, $replacement, $output);
 
	// parse usernames
	$pattern = '/[@]+([A-Za-z0-9-_]+)/';
	$replacement = '<a href="http://twitter.com/${1}" rel="nofollow">@${1}</a>';
	$output = preg_replace($pattern, $replacement, $output);
 
	// parse hashtags
	$pattern = '/[#]+([A-Za-z0-9-_]+)/';
	$replacement = '<a href="http://search.twitter.com/search?q=%23${1}" rel="nofollow">#${1}</a>';
	$output = preg_replace($pattern, $replacement, $output);
 
	return $output;
}