The Cocoon Hackaton is well underway, we've got perhaps 40-50 people here in the conference hall in Ghent, and there's been various breakout sessions that have occured. In particular the session about Cocoon Blocks was really interesting, with Pier, Ugo, and various others contributing to the new design of the Block management system behind Cocoon. Stefano even joined via video conference - right when we had the notebook projecting onto the wall (about 3m/3m!)
The Block management design sounds really cool - essentially the plan is to encapsulate each block within a classloader so that it can be primed with whatever statics are required to satisfy external library dependencies (ie. jaxp, logging, etc), and to expose proxied interfaces from the blocks to other blocks via an assembly system. This in turn will allow each block to be self-contained, and will allow the use of any arbitrary framework within the block for it's components (eg. Avalon, Spring, etc).
Certainly interesting stuff and will set us up well for the future. Part of the code is in Cocoon already in the form of Tani - the rest will be soon underway :)