Canonical URL Tag explained
Last week Google, MSN and Yahoo announced the use of the Canonical URL Tag to assist with sites that suffer from duplicate content issues. Please view the video below to get an explanation for what it actually means.
[youtube]http://www.youtube.com/watch?v=OxWSz5Pv0S4[/youtube]

The impact and importance of the canonical attribute comes from what it represents rather than what it is. It signifies a coming together of the Internet superpowers for the greater good…which makes a change from them trying to get one over on each other. I only hope that we won’t have to wait another couple of years for the next collective augmentation.
Hey Duncan, yes thats exactly what we were trying to get across. It just seems though that they only come together to release things that are not really needed anymore (outdated). Why did they not release something like this 5 years ago? I mean how hard can it be to come up with a tag that the spiders can read to show them how to stop canonical issues and duplicate content.
The search engines already know how to do filter out the rubbish without this. It may make their lives abit easier but in the end they are never going to publicly release anything that will make a major change without first being able to detect it themselves.
Just think of it like this. Five years ago most search engines could NOT filter out a lot of rubbish, so by releasing this tag then they would have just been open to even more spam, because people would know there is a major flaw in the algo and take advantage of it a lot more then they were before.