I've always wanted to pronounce that something has "jumped the shark". And now I'm here to tell you that it is Web2.0 itself.
My proof? The blasé daily reviews of a Web 2.0 blog like Mashable and the 40000+(!) feed readers of TechCrunch give you hints. And perusing Museum of Modern Betas, I felt a shadow and a threat has been growing in my mind. But it took this insanely long list of Web2.0 sites at VentureBlog to really crystalize it.
The fact that categories like "Bookmarking", "Community", "Economy" all have 20+ cutely-named indistinguishable competitors is the sign of the incipient utter doom of any site associated with "Web 2.0".
As soon as some wag coins the equivalent put-down phrase to "dot-bomb" people are gonna be fighting to differentiate themselves as so NOT web 2.0. They are gonna be un-rounding those corners and stripping the CSS of all the green, orange, and light grey faster than you can say: "Post-It notes for web pages"
Mark my words, six months from now, people will be re-positioning like mad to be as far from Web 2.0 as possible. So get ahead of the curve - disassociate yourselves while you still have time!