Merging two or more apps

This is an “OpenQuestion” on the rails wiki and I was wondering if
there’s been any progress or if anyone’s thinking about this problem?

Here is the link to the wiki page:

http://wiki.rubyonrails.com/rails/pages/HowToMergeTwoOrMoreRailsApplications

Basically, it would be nice to be able to have more than one app/
directory. The MVC from each would be loaded and all would be available.
It would really just be one app - the directory structure would simply
be more convenient. I suppose certain files will need single masters,
like routes.rb, but those would not be as difficult to track.

I know utilities like Piston are often suggested but those aren’t
perfect. Being able to leave an entire app/ directory untouched would
be ideal! For example, when basing an app around the framework of
another (this question has been raised repeatedly on and about the Beast
forum).