May I propose an add to standard library, namely method mkpath to class Dir.
(For non-unix-persons, the method makes all the directories needed to have
all directories in the given path.) Here's a definition (just hacked, once
tested, so beware):

  class Dir
    def Dir.mkpath(path)
      dname = ''
      path.split('/').each do |tmp|
        dname << tmp + "/"
        Dir.mkdir dname unless File.directory? dname
      end
    end
  end

I've coded this method twice, and I just tried to install one kit from RAA
implementing the same thing. I failed to install because it had a bug. So I
fixed it, but started to think that maybe people shouldn't recode this all
the time.

I'm afraid this version isn't good enough to be translated to C immediately
(like, I just noted it might be good to use File.SEPARATOR instead of '/',
maybe add some error handling, handle permissions and umask etc) but this is
just start for discussion.

	- Aleksi