From O'Reilly Radar:

The blogosphere has been buzzing today about O'Reilly sending a cease-and-desist letter to IT@Cork, demanding (yes, that's the legal term) that they not use "Web 2.0" in the title of their conference. I'd like to give the O'Reilly perspective, and clear up a few things. You'd be hearing from Tim, but he's off the grid, on a (rare) vacation.

O'Reilly and CMP co-produce the Web 2.0 conference. "Web 2.0" was coined when we were brainstorming the concept for the first conference in 2003. As noted in the letter to IT@Cork (sent from CMP's attorney, but with our knowledge and agreement), "CMP has a pending application for registration of Web 2.0 as a service mark, for arranging and conducting live events, namely trade shows, expositions, business conferences and educational conferences in various fields of computers and information technology." To protect the brand we've established with our two Web 2.0 Conferences, we're taking steps to register "Web 2.0" as our service mark, for conferences. It's a pretty standard business practice. Just as O'Reilly couldn't decide to launch a LinuxWorld conference, other event producers can't use "Web 2.0 Conference," the name of our event. In this case, the problem is that it@cork's conference title includes our service mark "Web 2.0," which the law says we must take "reasonable steps" to protect. We've also contacted another group that has announced a "Web 2.0 Conference" in Washington, DC this September.

I wondered where "Web 2.0" came from. It appears to not be about open standards and the like at all. Rather, it's more about Business 1.0.