Originally Posted by BestXXXPorn

Web 2.0 Design Style is normally characterized by:

Simplicity
Central Layout
Solid areas of screen real-estate
Simple Navigations
Bold Logos
Bigger Text
Rich Surfaces
Gradients
Reflections
Rounded Corners

And they basically follow better design principals than older sites. With more available options, sites are starting to look more and more like print work (which they should). A stronger focus on good typography is also a staple "Web 2.0" thing...

It's also a move to more application like functionality... AJAX has made a lot of things possible and so as a byproduct it has also changed designs... The popularity of some major players during the rise of "Web 2.0" (Digg, Twitter, etc...) heavily influenced what is considered a "Web 2.0" style... A lot of these design principals considered "Web 2.0" as also based in the tech itself like CSS3... Allowing for rounded corners, gradients, etc... to be created without using images allows for faster page load times and more robust options for designing using (X)HTML/CSS only. I believe this is a major part of "Web 2.0" designs...