I’m part of the Site du Zéro’s staff, a french website about computering (more than 8 millions pages view/month). I would be interested in writing something about Piwik, but as I can see the website is still only available in english (or maybe I missed something ?)
Are you looking for people to help you in doing tranlations for the website ? That I could help you with.
I searched for topics about translation in the Developer Zone, but found nothing.