Last week Google, Yahoo, and Microsoft announced support for a new link element to clean up duplicate urls on sites. The syntax is pretty simple: An ugly url such as http://www.example.com/page.html?sid=asdf314159265 can specify in the HEAD part of the document the following: <link rel="canonical" href="http://example.com/page.html"/> That tells search engines that the preferred location of this url (the “canonical†location, in search engine speak) is http://example.com/page.html instead of http://www.example.com/page.html?sid=asdf314159265 .
Announced last week? Did you use the search feature of this site? Here's a thread from 3-4 months ago about it: http://forums.digitalpoint.com/showthread.php?t=1233153
Yes, it has been around for quite a while. I have seen live example of it at http://www.astalavistaescorts.com/wiki_about_escorts.html - looks like such pages are reluctant into getting in the Googel index