I'm super excited about this release but I really, really envy the Russian Doll-caching through key-based expiration and the Turbolinks of the Rails 4 release. Man I really wish django would package all the JS magic Rails comes with.

Am I correct in my understanding that the doll caching is based on .updated_at?

Are there any mature 3rd party apps that cover this ground?

Not that I have found so far.