Web 2.0 has been around since Amazon introduced user reviews of products in the late 90's. Web 2.0 is not a style (even though most people think that's all it is), or a state of mind, or a type of coding.... it's about a site content being produced by users.
And for anyone who wants to know about web 3.0.... just make sure your site looks good on mobile devises. Which CSS can deal with now!!! So go jump on the 3.0 bandwagon before it leaves the station.
For the record, there are NO VERSIONS to the web. So, just because some marketing puke tells you it's 2.0, or 3.0, or whatever.... it's still the same internet we all use.
Don't believe the hype!