Google is now supporting link rel=”canonical” relationships specified in HTTP headers. Evidently this was heavily requested, as the feature is in response to webmaster feedback. The syntax can be found in this document. Google Webmaster Trends analyst Pierre Far outlines …

Google announced that it now offering cross-domain support of the rel="canonical" link element. If you are unfamiliar with this link element, Google’s Matt Cutts discussed it with us here. Basically, it’s a way to avoid duplicate content issues, but until now, you couldn’t use it across domains.