For every complex problem there is an answer that is clear, simple and wrong
--H.L. Mencken
Put bluntly, I think lumping XmlHttpRequest, DOM, Flash MX and any other dynamic browser-based solution into a single name is misleading. I've always hated crap like "LAMP" and other cutesy names. They only serve to obfuscate the meaning of the technologies and to create a hype-of-personality surrounding BS terms that never meant anything in the first place, even alienating people who are not "in the know."
We don't need a "Web 2.0" and the name itself is misleading - all supposed Web 2.0 stuff is still TCP/IP-based. To me Web 2.0 would imply some different kind of transmission protocol like mind-reading. Ooh, I have a catchy name to define this exciting new protocol that's better than "Web 2.0": "Synapse Telepathy-based Universal Protocol/Interpersonal Dynamics."