Cocoon is Cool!
Cocoon is unbelievably cool. It is also an unbelievably vast swarming pile of chaos and confusion. Parts of that confusion can probably make web application (heck, it can probably be used to generate desktop applications via perl - or even better, generate JNLP and bytecode on the fly). It is a little bit insane.
FlowScript has the potential to be the coolest thing to happen for a long while in webapps. Right now it looks a wee bit clunky, but... it seriously re-writes the way web page flow can work. They (Cocoon team) argue that it changes web apps from finite state machines toprocedural scripts, but i sort of disagree. I really only disagree because you are still stuck in the problem of needing the finite set of pages to sendPageAndWait() with. You can change your flow between the pages, but it is still an FSM - just with a nicer way of describing the state transitions. Workflow type things in particular seem very interesting under this. As FlowScript is scripted, it is hopefully possible to generate it dynamically, meaning ye bigge olde enterprise-e rules-e engines can do cool stuff.
I think Cocoon really needs to be factored into several projects all under the "Cocoon" unbrella (like the Jakarta umbrella) which I guess is going on now that it is a top-level project. So many pieces of it are orthogonal to other pieces that this shouldn;t be terribly difficult. Once that happens and it becomes easier to navigate and grok everything that is possible, wow.