What is Web 2.0?

I read with interest the Larry Sanger article on Web 2.0 in education. This is obviously an extreme, but I can already see small elements emerging in Secondary education. Given that education as a whole changes very slowly, I wonder if we would, or could, ever reach this level of independence.
The online environment, whether through mobile devices or desktop devices, is obviously here, though a computer/device is still only a 21st century pencil. It is what can be done with it to enhance learning and skills acquisition for students which must be the measure for accountability.
The potential is there. It's the practical application that is the interesting bit!