Duplicate content has been a hot topic among webmasters and our blog for over three years. One of our first posts on the subject came out in December of '06, and our most recent post was last week. Over the past three years, we've been providing tools and tips to help webmasters control which URLs we crawl and index, including a) use of 301 redirects, b) www vs. non-www preferred domain setting, c) change of address option, and d) rel="canonical".
We're happy to announce another feature to assist with managing duplicate content: parameter handling. Parameter handling allows you to view which parameters Google believes should be ignored or not ignored at crawl time, and to overwrite our suggestions if necessary.