Any development on this discussion in the last 4 years?
Web 2.0 usually incorporates RSS, XML, social media including Facebook, Twitter, and other elements like DISQUS. As such, I see Web 2.0 involving mostly marketing and promotion tools for your webcomic, more than acquiring an income - of course, the greater your audience, the more likely you are to acquire an income through them.
Project Wonderful (http://en.wikipedia.org/wiki/Project_Wonderful) by Dinosaur Comics' artist Ryan North is an interesting ad tool that many artists use. All the webcomic artists I know say in interviews and what not that the best way to get money is through utilizing online stores (like http://www.topatoco.com/), and selling t-shirts and compilation books you've made about your material.