Apologies to Tim O'Reilly but maybe it's time to take "Web 2.0" out to pasture. To be blunt, Web 2.0 has out-lived its usefulness. It's stale, it's difficult to define (check out this Slate story and InfoWorld post) and fails to resonate once it moves into the mainstream. Nevertheless, it continues to be embraced by marketers, entrepreneurs, journalists and conference organizers because it is the widely-accepted phrase to describe how the Web has become a place to do things and share information. Newsweek made an attempt to rebrand "Web 2.0" in a recent cover story by proposing "Live Web" as an alternative, while "web 2.0" (owercase "w") has quietly started to be adopted recently. While "Live Web" is commendable, it is too simplistic. Personally, I like the idea of the "Dynamic Web" to describe how the Internet has become a place to do things - be it create content, collaborate, buy and sell, register your children for sports (which certainly beats lining in hours before the doors officially open), file invoices, etc. Dynamic Web works for me because it clearly makes a distinction with Web 1.0, which was mostly a static environment. This stage of the Web development deserves something better than Web 2.0 because there is a lot of exciting things happening for developers, entrepreneurs and Web users.
Update: Perhaps another sign that Web 2.0's time has come was Yahoo's April Fool's joke in which the company announced it had acquired the Web 2.0. "All of it. All the people, the round cornered boxes, the crazy business ideas, and pastel colors. So if you want to be Yahoo company, just create a Web 2.0 startup and you'll automatically be part of Yahoo's big family."
Update II: Dion Hincliffe has a lengthy Web 2.0 post that talks more to what's happening as opposed to whether the term "Web 2.0" still functional.