I played around with Cocoon in mid 2001 or so. I first thought the concept was interesting and enjoyed making some sites, but the performance then was... well... Now, it is 2003, the performance is good and the framework is the most original I have ever seen. It is well thought out, it is clean, and I've been very impressed. A lot has changed!
I think the crew that has worked on Cocoon should somehow be honored, maybe a lifetime supply of beer? They have some of the most original ideas: Blocks, XSP, Flow, XMLForms. Just when I thought I knew how things should work in web design, I had to throw some concepts out the window, rethink how I approached building web sites. Cocoon 2.1 simply knocked the wind out of me.