Gimp 2.7.3 has been released but no one ports it to OSX already here is an ugly working way.
EDIT: The macport is now up to date so no need to do this anymore !
It needs a lot of dependencies, get it via macports:
run port sync
Edit /opt/local/var/macports/sources/rsync.macports.org/release/ports/graphics /gegl/Portfile
Change version to 0.1.6 and master_sites
remove the path line about atch-gegl-buffer-gegl-buffer.c
Edit /opt/local/var/macports/sources/rsync.macports.org/release/ports/graphics /babl/Portfile change version and master_sites
port install babl
port install gegl
port install aalib iso-codes libmng librsvg libexif libwmf poppler openjpeg lcms2 poppler-data libwmf poppler openjpeg lcms2 poppler-data py27-gtk py27-cairo py27-numpy py27-gobject librsvg libopenraw dbus-glib
Download gimp 2.7.3 and uncompress it
export PYGTK_CFLAGS=“-I/opt/local/include -I/opt/local//Library/Frameworks/Pyt hon.framework/Versions/2.7/include/python2.7/pygtk-2.0 -I/opt/local/include/glib-2.0 -I/opt/local/include/gtk-2.0 -I/opt/local/include/atk-1.0 -I/opt/local/include/cairo -I/opt/local/include/pango-1.0 -I/opt/local/include/glib-2.0 -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng14”
./configure –prefix=/opt/local/gimp-2.7.3 –without-mac-twain
make -j 8