I have exactly the same questions..
For an application like facebook, gmail, etc., (not a crm like capsule) that will have 500 million users and more, it does make sense to utilize the memory and cpu of the clients and keep the most, if not all of the state on the client side..
for instance, in facebook when you wish to see older posts, you don't paginate, more records are added to the bottom of the page.. it uses ajax extensively, record operations are done via pop ups and dom manipulation..
i like how seam ties together db, rules, in a server centric world but it makes more and more sense to ditch jsf and move towards the gwt, for it seems like the most mature and somewhat complete client side framework to me -i am open to suggestions-.. vaadin, as far as i can understand, just replaces jsf with gwt but still keeps a stateful server side presence and just for that reason alone, i don't think it is the answer for a facebook scale application..
so.. if not going to use jsf does it still make sense to start a
seam web project?
what jboss tools/configuration/etc. do people use for a gwt centric and j2ee/jboss project?