Comment on Google Authorship Tutorial by SEO Dave.

Google Rich Snippets Tutorial Yes you have to add the rel tagged link on every page of the site since you can have multiple authors on a site, so every page is an individual island authorship wise.

What I do is add it as a custom menu link sitewide, that way every page is covered. Don’t like HAVING to add a link, but if you want the authorship…

I don’t know how much if any value Google gives authorship right now (guess currently not much, if any), I suspect eventually it will be important (though not the be all and end all of SEO). Maybe a case if an author tends to be published on quality websites, there’s more ‘trust’ given to that authors content. After all there’s lots of websites where there are thousands of authors, some of the content is great, some SPAM, but the sites as a whole get a lot of visitors and it does make sense to rank some authors content above others. If Google moves in that direction it works both ways, if you tend to create spammy content last thing you want to do is claim ownership of it :-)