Prebuilt binaries are now at:
"GNU D Compiler for Mac OS X"
http://gdcmac.sourceforge.net/

The following builds are available as either PKG or ZIP*:
GDC 0.12 for Panther (Mac OS X 10.3, based on GCC 3.3.6)
GDC 0.12 for Tiger (Mac OS X 10.4, based on GCC 3.3.6)

After installing the PKG package, you can begin compiling
D programs directly with either "gdmd" or "gdc" commands.
(Since this version installs the programs under /usr/bin)

Share and Enjoy,
--anders

*PS. The zip files have the binaries, no fancy installers.