Parse a tweet's text with PHP and regex

gistfile1.php

<?php

/**
 * Regex taken from http://saturnboy.com/2010/02/parsing-twitter-with-regexp/
 */
function parse_tweet($text) {
  // Parse links.
  $text = preg_replace(
    '@(https?://([-\w\.]+)+(/([\w/_\.]*(\?\S+)?(#\S+)?)?)?)@',
    '<a href="$1">$1</a>',
    $text);

  // Parse @mentions
  $text = preg_replace(
    '/@(\w+)/',
    '<a href="http://twitter.com/$1">@$1</a>',
    $text);

  // Parse #hashtags
  $text = preg_replace(
    '/\s+#(\w+)/',
    ' <a href="http://search.twitter.com/search?q=%23$1">#$1</a>',
    $text);

  return $text;
}