The promise of the web has always been frictionless communication, ease, speed, and joy.
Yes, the term “Web 2.0” is “a big, vague, nebulous cloud of pure architectural nothingness”. The lack of it’s specificity is a problem.
I’ve also heard the cynical:
Five years ago web developers failed at fulfilling the web’s promise. It’s taken us 5 years to get over it – and develop technologies mature enough to try again.
“Web 2.0” has very little to do with technology and far more to do with a New Found Optimism. Something we needed – desperately.
That said, saying you’re a Web 2.0 company is like telling the cool kids you’re cool. It’s one of the easiest way to get stuffed in a ball bag.