Actually, it's just a name that many use, it doesn't really mean anything specific, i.e. different meaning to different people.  In theory, one could call web 2.0 when people stopped putting together static HTML pages and started doing dynamic ones; then there was a personalization phase, which by these standards could be called web 3.0 and now we're even past that, with Ajax, social stuff, web-based apps, like my Record Sage

 So, I'm sure the cycle will continue, new innovations will come to life and the evergoing evolution will continue, regardless of someone coming up with a term for some elements of it or not, as they did with web 2.0.  That's the way I see it.