How important are they?
Is there a code to load these automatically in each page

Personally, I'm not convinced they are needed if you are defining the version of the preferred address in your web.config or .htaccess file.
I would like to hear other comments though.

[quote]Matheny - Is there a code to load these automatically in each page[/quote]

I was thinking that the availability to add a canonical tag in the product admin in the same way as the Page Title & Meta Description tags are able to be. With an ecommerce site it seems hellishly easy to end up with products that are deemed almost identical as well as trying to avoid that from occurring can be a real time consumer.

I'm certainly no expert but I was reading the following Google article [url]https://support.google.com/webmasters/answer/139066?hl=en[/url]

As with a lot of web design stuff, at best it can make ones toe nails itch and sometimes ones head explode

Will - Bolton Manchester UK

V45 you are spot on and Google is not liking duplications.

Craig Matheny
LazerMmodels.com