Using Google's Authorship Markup – How?

Yeah, I would like to know the same.

It looks like you need to add rel=”author” to a link to your author page and rel=”me” to a link to a Google profile. – authorship explanation

Google Authorship has nothing to do with tags/taxonomy as the terms apply in WordPress.

Essentially, what you do is:

1) Create a google profile.
2) Add a link with the rel attribute set to “author” on any content belonging to the owner of the google profile you created.
3) Fill out a form at Google.

More detailed instructions are here:
https://www.google.com/support/webmasters/bin/answer.py?answer=1408986

Thanks for this tip @kionae