The Google Webmaster Central team has developed a new feature to assist with duplicate content issues. It’s called parameter handling and it allows you to tell Google what to ignore or pay attention to when it comes to indexing your site.
This is great for the SEO that doesn’t have quick access to add code regarding duplicate content to a website. However, these parameters will be treated as “hints” by Google. Getting that code or URL rewrites into your website are still ultimately important.