Who the hell CARES about the term?
Gmail is a good application. Digg was a good idea but it didn't scale. You can argue about Web 2.0 all you want, nobody cares. And you can go out and make money right now, and that's a fact regardless of whether you're 2.0 or 3.0 or whatever in between.
I never got the reason behind the "2.0" buzz. I never will. It's such a pathetic waste of time.
http://www.oreillynet.com/pub/a/oreilly/tim/news/2005/09/30/...
The exception to 'social != $$$$' is of course Google's page rank algorithm which is essentially a social/collective intelligence system. The financial success of first Google then other companies is probably what motivate the term more than anything else. It is a shorthand way of saying
'The internet is not a financial failure. It's back and we it doesn't need all those MBA's who helped create the crash in the first place.'