Sorry for the delay, I've been busy with personal matters.

Attached is an initial outline of the repository format I'm
planning, which is intended to address the major issues
and leave room for growth.  The idea is anyone can
provide their own repository, and implementations can
write their own tools (or modify existing ones) to download
packages from a repo.

Of course, there will be a central repo and a
common tool which will aim to support all R7RS
implementations, and we need to decide on a name
for it.  Suggestions include:

  * CSAN - obvious analogy to CPAN
  * Scheme Wizards Academy - play on our academic
    reputation, can be called the Academy for short, or
    potentially "Schwa".
  * Nineveh - ancient library
  * The Den - heard on #scheme

More suggestions are welcome, we'll probably take a
vote shortly.

I'll try to make the install tool available shortly,
though will be focusing on final draft editing first.

--
Alex