As much as I hate the whole web 2.0 bullshit, I've found myself wondering if I should be using the term as this is what so many clients have heard about and latched on to. It's become a very popular buzz word even making as main stream as car commercials, e.g. nissan shift_2.0.
As much as people hate it I think we will all have to start embracing the term. Even though the "web" does not have versions the term does mark a significant change in the way web applications are built, designed and used.