I just found out about this one earlier today and I have to say – that the big three got together on this one is a great step for their respective indexes and a great way to control duplicate content issues.
I can’t possibly outline what the new tag is an does any better than Matt Cutts.
And to make matters worse (in the form of making the sources I reference appear VERY small) I’ve got another video for you. So that’s two posts in one day, both referencing Matt Cutts and both with interviews from WebProNews. There are more resources below. But first – the video:(Video removed – no longer available)
Here some additional followups and resources related to the new Canonical tag:
Joost comes up with some great plugins for common content systems. Click here for more information and perhaps to contact Joost directly and find out when he sleeps.
Jim Hedger writes about this over on the Webmaster Radio blog (Note: link removed as the post has been removed in a redesign).