I think the other thing that is tied to the 1.0-2.0 evolution is that with increased user generated data (because of these uploads) the surveillance economy model for revenue exploded. In web 1.0 you really couldn't get enough information from simple search tracking for a valuable dataset, but once folks started blogging and using social media, there was a much bigger signal to monetize.

By definition, this came after the 2.0 transition, so maybe call it Web2.5?