An impressive piece of tech but I'm not really convinced this is a good approach, especially after comparing their photo demo with Sproutcore's (http://cappuccino.org/learn/demos/FlickrPhotoDemo/ vs. http://www.sproutcore.com/static/photos/) which suggests to me that Cappuccino has serious speed problems. The situation is likely even worse on old machines with older browsers as I'm on a relatively up-to-date machine using FireFox 3.