twitterize

// The function that links the hashtags, urls and usernames into links...
function twitterize($raw_text) {
    $output = $raw_text;

    // parse urls;
    $output = preg_replace(
    '@(https?://([-\w\.]+)+(/([\w/_\.]*(\?\S+)?(#\S+)?)?)?)@', '<a href="$1" target="_blank">$1</a>', $output);

    // parse usernames
    $output = preg_replace(
    '/@(\w+)/', '<a href="http://twitter.com/$1" target="_blank">@$1</a>',$output);

    // parse hashtags
    $output = preg_replace(
    '/\s+#(\w+)/', ' <a href="https://twitter.com/search?q=%23$1" target="_blank">#$1</a>', $output);

    return $output;
}