This sounds just great. I have used Rails for some time now but have always been reluctant to really get in there and take a look around because by the time I got to it, Rails was already a seemingly huge behemoth of a code base and I didn't think I could devote enough time towards getting my head around it. These kinds of changes to the organisation of the code make me feel like maybe I have a chance at delving into the now more discrete internals and in the process, becoming a more efficient user of the framework and perhaps one day, even give something back.

One nice immediate benefit of all of this is that ActionMailer gets all of the functionality of ActionController in a clean, intentional way. Everything from layouts and helpers to filters is using the identical code that ActionController uses, so ActionMailer can never again drift away from the functionality of ActionController (as ActionController itself evolves).

I particularly like the sound of this, bringing ActionMailer more into the fold as it were. I've had a number of occasions to need to use ActionMailer and it's not always been a pleasant experience.