We are now approaching the next Texinfo release.  Here is my question:
        is the collective wisdom that I should write this cookie now, before an
        Emacs release has been made that supports it?  Or should I wait?

    I think the time to add it is now.  

Ok, I will.

    But isn't this a rather ugly way to do it?

It is ugly, but it is backward-compatible.

In the mail last year, you suggested
* Index:
instead of
* Menu:
in index nodes, which is prettier -- but then old info readers wouldn't be
able to read new info files properly, which seems too big a drawback to me.

The ^@^H[ stuff, which we invented for images, will also give us an
extensible mechanism, once Emacs Info ignores (and does not display) any
directives it doesn't know what to do with.  (I'll attach a test file.)
So in that sense, it is not *too* ugly a solution.

BTW, can someone volunteer to do that?  I've asked before, but no one
answered.  Maybe we should look for a volunteer to be the official
maintainer Emacs Info?  Unfortunately, I don't have time to do it myself.

Thanks,
k