Firstly, O'Reilly is only claiming to own the "Web 2.0" service mark as it pertains to conferences and events. http://tess2.uspto.gov/bin/showfield?f=doc&state=lclroo.2.1 Everyone has the right to protect his intellectual property. But it appears that O’Reilly may not have protected his. A genericized trademark is “a trademark or brand name which is often used as the colloquial description for a particular type of product or service as a result of widespread popular or cultural usage.” http://en.wikipedia.org/wiki/Genericized_trademark I have read that in America and other countries, for years, there have been numerous conferences and other events with “Web 2.0” in the name. http://blog.softtechvc.com/2006/05/the_web_20_lega.html If this is true, then since O’Reilly and his company did not previously enforce their rights and send Cease & Desist letters to those conference organizers, it seems to me that “Web 2.0” has been allowed to become a genericized trademark. Hence, trademark rights may no longer be enforceable or at least it may be difficult for O’Reilly and crew to now legally enforce their rights. A long list of other genericized trademarks: http://en.wikipedia.org/wiki/List_of_generic_and_genericized_trademarks Also, see the very brief opinion of The Trademark Blog on this topic: http://www.schwimmerlegal.com/2006/05/web_20_v_web_20.html