Hey All,
It isn't 100% complete yet, but I've decided to cut a 0.0.1 release for IntercoolerJS:
http://intercoolerjs.org/
Intercooler is a Partial View Controller framework, where AJAX responses are HTML fragments (partials) that are swapped in for existing content, based roughly on the Basecamp 2 approach.
If anyone else is interested in working on or using the project, please let me know: there is still tons of interesting work to do (e.g. back-button/pushState() support)
I think that, for many apps, this might be a good way to get 90% of the UX advantages of a thick Javascript MVC framework, at a fraction of the complexity.