Hi. I was using this great lib and figured out that the getAttributes function was not working when fetching more than one attribute. Here is a little update for your function :

    public static function getAttributes($domain, $item, $attributes = null) {
        $rest = new SimpleDBRequest($domain, 'GetAttributes', 'GET', self::$__accessKey);
        $rest->setParameter('ItemName', $item);
        if($attributes !== null)
        {
            if(is_array($attributes))
            {
                foreach($attributes as $i=>$name)
                {
                    $rest->setParameter('AttributeName.'.$i, $name);
                }
            }
            else $rest->setParameter('AttributeName', $attributes);
        }

Usage : getAttributes("domain","itemName",array("att1","att2"…))