We've discussed in the past Facebook's aggressive
claims of trademarks on pretty much any use of "face" as a prefix or "book" as suffix. The company did eventually get a registered trademark on some uses of "Face", but the "book" part has proven more difficult. That said, you really don't have to register a trademark, but can assert common law trademarks based on use alone, which can be pretty effective. Still, the folks at Ars Technica noticed that Facebook has now slipped a little nugget into its user agreement, saying that if you use the site you effectively agree to the company's claims on a variety of trademarks
. It had already included a bunch before, but has now added "book" to the list.
Ars suggests that this could strengthen Facebook's claims against sites, but I'm not convinced. While clickthrough license agreements that no one reads may have some
force under law, I would think that any company using the phrases legitimately could make a good case that such a clickthrough in no way diminishes their rights to make reasonable use of "face" or "book." Really, though, Facebook should shackle its trademark lawyers a bit and tell them to chill out in all but the most egregious cases. Being a trademark bully is no way to build a company.