Facebook has sued a teachbook.com, a site devoted to teachers and learning, because it has the word “book” in its name. The site looks nothing like Facebook and the site founders say they picked the word “book” because the site is about teachers and education.
I doubt that Facebook has a real trademark infringement case here, but it really doesn’t matter. Teachbook has 20 users and not much money. Simply defending themselves in a lawsuit would probably kill the company, so they’ll change their name, and Facebook will effectively own the word “book”.