What is web 2.0? For Wikipedia it is enough if the site is interactive. For me it is more than that. Not only the interactivity of the site is making it web 2.0 because then a forum is also web 2.0. For me a web 2.0 site is a mix between interactivity and feeling.
Well for the feeling part I have a nice tutorial. www.webdesignfromscratch.com wrote a nice article how to make the design for your website look like a web 2.0 design. This is not giving the entire feeling of a web 2.0 site, but who cares if the site looks nice?