I wish people would learn what the term "Web 2.0" is all about. It is not simply a design style, though that is part of it due to the influence of accessibility, usability, etc, etc. As far as I'm aware, there isn't a web gallery showcasing only sites falling within the "Web 2.0" idea.

Many of the popular "CSS" galleries do display sites belonging to 2.0 but only because there are some sexy designs coming out -- there are equally ugly websites coming out, not getting showcased, which would comfortably be labelled "Web 2.0" also.