I hate buzzwords, but I agree with Kathy when she says that Web 2.0 is more than just a buzzword. It is not a meaningless term (or as Letterman might say, it's "not nothing"). Kathy makes the ever-important distinction between buzzwords (bad) and jargon (good). Ultimately, she says, Web 2.0 gives us vocabulary to discuss an otherwise complex and abstract idea and allows us to have more intelligent conversations about what's really going on.
While this vocabulary does facilitate discussions, it also allows us to be lazy and gloss over what is really important. Much like architecture, the Web 2.0 principles are important as long as they are consciously applied and we don't lose sight of why the feature matters in the first place.