A few months ago, I rocked the techmeme world by standing on my soapbox and proclaiming loudly that Web 2.0 doesn't exist- and if it does, it is no more than a marketing gimmick.
Well, now I have proof. Read the letter at the top of this post. Pay special attention to the start of the third graf.
There you have it. Web 2.0 is nothing more than CMP's applied-for service mark, a moniker to market conferences. If you want to use this overgeneralized term to talk about everything from YouTube to Flickr, from MySpace to Digg as components of some sort of unified, next-generation, participatory Web, go ahead.
But just like any other trademarked ad slogan, it isn't really yours to use as anything more than a lazy-thought shortcut. Try to make money off this marque, by, say, doing a conference that uses this term, and CMP's legal eagles are gonna come after ya.
Their grounds for doing so would be the service mark app they have filed. Here's a screencap.