Google puts under surveillance the content authors in blogs
Matt Cutts, header of webspam team at Google, has warned about the content taken or acquired in article directories and about the guest authors on blogs. For the search engine they are a source of spam that wants to eradicate. The first conclusion about his words is that require authors to register in Google Authorship in order to avoid penalty.
Post in Spanish: Google pone bajo vigilancia a los autores de contenido en blogs