I was reading my SEO RSS feeds and an article about duplicate content in WordPress caught my attention – Guide to Bringing Your WordPress Blog Up to Today’s Google Algorithm Standards.
The article noted that WordPress creates duplicate content through taxonomies. The duplicate content is made when the category, tag, date or author archive page is indexed. The Yoast WordPress SEO plugin can mark these as “noindex, follow”. This is done on the Taxonomies and Other tabs in the plugin.