Why Tim O'Reilly cannot legally own Web 2.0??

IT@Cork receive a Cease and Desist from CMP

Ok, so next time when you use the term "Web 2.0", be prepare yourself to get a legal notice from lawyer of O'Reilly. News is that IT@Cork wants to organize an upcoming Web 2.0 half-day conference and they got a legal notice from O'Reilly demanding them to immediately cease and desist from using term "Web 2.0" in the title of the event. And funniest part is that Tim O'Reilly actually got an invitation we well for the same conference meeting.

O'Reilly trademarks "Web 2.0? and sets lawyers on IT@Cork!

And here is that cease and desist letter:

That's Great! But problem here is that Tim O'Reilly can not legally register the term "Web 2.0" as service mark, because someone else has already using this term for commercial purpose since 2002.

It's a book published by Dermot A. McCormack in 2002: Web 2.0: The Future of the Internet and Technology Economy. And so Tim O'Reilly can not claim that he coined the term and register or try to own the term "Web 2.0".