On the subject of frameworks:
Is there a standard install directory for frameworks? On some
Portfiles (notably the libsdl*-framework ports), frameworks are
installed to /Library/Frameworks. On others (such as python2[45]),
they are installed to ${prefix}/Library/Frameworks.
Personally, I think the latter (in ${prefix}) is much better
practice, though it might be a good gesture to to provide a symlink
within /Library.
Once I have an answer on this, I'll put in a fix to mzscheme.
Chris