Emacs for Mac OS X now has a separate webpage:
Here is a patch to Emacs 21.1 to allow it to build
and run under Mac OS X:
http://www.cse.cuhk.edu.hk/~akochoi/emacs/macosx/emacs-21.1-2-mac.patch.gz
The instructions for applying it are contained in
the file:
http://www.cse.cuhk.edu.hk/~akochoi/emacs/macosx/readme.txt
The GUI code is basically a Carbonized version of
that in Emacs 21 for Mac OS classic. The Unix API
of Mac OS X is used to implement synchronous and
asychronous subprocess support and networking
support. A new `unexec' for the Mach-O executable
file format, written entirely from scratch
(src/unexmacosx.c), provides support for
`dump-emacs'. The autoconf/makefile mechanism is
adopted so Emacs will built on Mac OS X with the
Developer Tools installed.... read more
Please take a look at http://mac-emacs.sourceforge.net/ for information on where to download it.