My favorite Warlick insight from his 2 Cents Worth blog:

"Conservatism and conformity necessitate control, and the spirit and the affect of Web 2.0 are to democratize control and make it personal. When teachers are released from district managed portals, and allowed to shape their own personal learning networks, when they are granted a voice and ear to a global conversation about education, when students begin to take a more active role in affecting the “what” and “how” of their own learning, then education changes, and the barriers between the “classroom” and “world” start to disappear."

For me it answers "Why Web 2.0?" - and this will be its lasting legacy. I believe many Web 2.0 tools will fade to oblivion but not their democratizing nuggets.