in addition to mbrubeck's comment, i'd say that javascript has grown from merely providing neat actions to webpages, to being model, view and controller.

at my startup we (er, the other developer) ported/mimic'd django's mvc to javascript. we're building a firefox extension, so this is particular critical as the extension must provide the full mvc for the "website."

edit: as a ff extension, our models are backed by sqlite files. in jester and kiwi are models objects? that is, are these frameworks purely for client-side applications, or for javascript-server stuff?