For me, the big thing about web 2.0 is the amateur revolution.
Easy to publish
2.0: anybody can publish its content text, photos and videos very easily, as easy as sending an email.
1.0: was too complicated, home page builders, hosting and too much html code. News is simplicity.
2.0 amateurs can get their content known easily and for some of them reach a broad audience thanks to the efficiency of search engines enabling the long tail.
1.0 search engines were sending most of of their audience to the mass news sites and already known brands such as CNN and the like. Now amateur content has the same voice or even a louder one in some cases.
Control of your own data
2.0 your content belongs to you (like in Second Life) and you can export it or get it back easily (like in Flickr, Typepad)
1.0 when you upload your data the sites own it and don’t let you get it back.
Joi says that sites that do not repect this last point belong to the bubble 2.0 and that YouTube is one of these as there is no way to export easily your video, unlike eyespot or blop.tv.
How about web 3.0, what is it for you ? Here is a tentative. I should try to get him to speak at LeWeb3 to explain us better.