How would you define Web 2.0 – and what’s next?

I’ve been asked a few times lately “what is web 2.0?” and I’ve been told “I want my site to be web 2.0 compliant” (which kind of made me laugh.

I like to think of Web 2.0 as more of a practice than something to be compliant with.

If I were to be asked by a novice, “What is web 2.0?” I think I’d sport the response “Web 2.0 is about an Internet that engages”. It’s an answer that encompasses a multitude of definitions.
According to Wikipedia – “”Web 2.0″ refers to what was perceived as a second generation of web development and web design. It is characterised as facilitating communication …”
I’m not quite sure what they mean by “what was perceived…” Surely Web 2.0… is? Isn’t it?

I prefer the definition found on Twinity.com – “Web 2.0 does not refer to any specific change in the technology of the Internet, but rather the behavior of how people use the Internet. …”

Yes, ‘Web 2.0’ types sites might look a little sleeker, they might have glossy and reflected logos, dropped letters and pretty colors (see graphic) but some would argue that the design type that some would define as Web 2.0 is merely a natural evolution in design. i.e in history text changed from Ye Olde English to….Arial, right? isn’t Web 2.0 the next step?

What do you think? How would you define “Web 2.0?” What do you imagine Web 3.0 being? are we already there?