Web 2.0 - design guidelines

I was googling to find some resources about web 2.0 design trends. I say web 2.0 design trend because the web sites' designs have changed drastically since the introduction of web 2.0 services. I found this as a good article on the topic.

web 2.0 how-to design style guide

It gives good explanations on the changes to the web design with examples and some links to more information.