Whew! QGIS 2 on Mavericks built using only Homebrew packages (i.e. without KyngChaos) \o/ -- WARNING: A _major_ assumption here is that your Homebrew PREFIX is /usr/local . -- DISCLAIMER: It worked for me. YMMV

install.sh

#!/bin/bash

# Run this:
#
# curl https://gist.github.com/nicerobot/7664605/raw/install.sh | bash -s do-sudo
#
# which will run:

[ -f qgis2-homebrew-build.sh ] || {
	curl -O https://gist.github.com/nicerobot/7664605/raw/qgis2-homebrew-build.sh
	# If i download it, i'll remove it
	trap 'rm -f qgis2-homebrew-build.sh' 0 1 2 3 15
}

bash ./qgis2-homebrew-build.sh ${*}

qgis2-homebrew-build.sh

#!/bin/bash

# There's a few hoops to jump through but i mostly just followed the QGIS
# repository's INSTALL instructions for MacOSX. Also, there may be a few dependencies
# missing due to the fact that, when i was creating this, i think i already had
# many of the dependencies installed.

SELFD=$(cd -P $(dirname ${0} >/dev/null 2>&1; pwd))
SELF=$(basename ${0})

# This sudo is called from the following block if "do-sudo" is the first argument.
[ "${1}" = 'sudo' ] && {
	which brew || exit ${LINENO}

	brew install qt --HEAD

	# Now install other dependencies normally.
	for i in python bison pyqwt sip qscintilla2 spatialindex grass; do
		[ -L /usr/local/opt/${i} ] || brew install ${i}
	done

	# Install qwt 6.0.1
	[ -L /usr/local/lib/qwt.framework ] || {

	# Use qwt 6.0.1 because QtPolar must be : 6.0.0 <= QtPolar <6.1.0

	cd /usr/local
	brew checkout 4392eba Library/Formula/qwt.rb
	# Have to patch Library/Formula/qwt.rb with 6.1.0 lines so that it'll build using libc++ instead of libstc++
	# Could probably also have simply patched the 6.1.0 formula to download the 6.0.1 tarball.

	patch Library/Formula/qwt.rb <<-'PATCH'
		--- a/Library/Formula/qwt.rb
		+++ b/Library/Formula/qwt.rb
		@@ -13,7 +13,15 @@ class Qwt < Formula
		       s.gsub! /^\s*QWT_INSTALL_PREFIX\s*=(.*)$/, "QWT_INSTALL_PREFIX=#{prefix}"
		     end
		 
		-    system "qmake -spec macx-g++ -config release"
		+    #system "qmake -spec macx-g++ -config release"
		+    args = ['-config', 'release', '-spec']
		+    # On Mavericks we want to target libc++, this requires a unsupported/macx-clang-libc++ flag
		+    if ENV.compiler == :clang and MacOS.version >= :mavericks
		+      args << "unsupported/macx-clang-libc++"
		+    else
		+      args << "macx-g++"
		+    end
		+    system 'qmake', *args
		     system "make"
		     system "make install"
		   end
PATCH

	}

	exit 0
}

#
[ "${1:-skip-sudo}" = 'do-sudo' ] && {

	[ -w /usr/local ] || SUDO=sudo
	${SUDO} ${SELFD}/${SELF} ${SUDO} || exit ${?}
	# If sudo completes successfully, continue with QGIS build.

}

# If not already in QGIS directory,
[ -d .git ] && grep QGIS.git .git/config || {
	# Then check if it exists, otherwise, clone it.
	[ -d QGIS ] || git clone https://github.com/qgis/QGIS.git
	# And get into it.
	cd QGIS || exit ${LINENO}
}

# 
[ -d build ] || mkdir -p build
cd build || exit ${LINENO}

cmake -D CMAKE_INSTALL_PREFIX=${HOME}/local \
  -D CMAKE_BUILD_TYPE=MINSIZEREL -D ENABLE_TESTS=FALSE \
  -D WITH_INTERNAL_SPATIALITE=FALSE -D WITH_PYSPATIALITE=FALSE \
  -D SPATIALINDEX_LIBRARY=/usr/local/lib/libspatialindex.dylib \
  -D SPATIALINDEX_INCLUDE_DIR=/usr/local/include/spatialindex \
  -D QWT_LIBRARY=/usr/local/opt/qwt/lib/qwt.framework/qwt \
  -D QWT_INCLUDE_DIR=/usr/local/lib/qwt.framework/Versions/Current/Headers \
  -D BISON_EXECUTABLE=/usr/local/opt/bison/bin/bison \
  -D WITH_APIDOC=TRUE \
  ..

make -j	$(/usr/sbin/sysctl -n hw.ncpu)

# Hack to ensure QGIS has Homebrew's `python` before the system's so that `sip` is available.
[ -x output/bin/QGIS.app/Contents/MacOS/QGIS_ ] || {
	cd output/bin/QGIS.app/Contents/MacOS || exit ${LINENO}
	mv QGIS QGIS_
	printf '#!/bin/bash\nPATH=/usr/local/bin:${PATH} $(dirname ${0})/QGIS_\n' >QGIS
	chmod +x QGIS
}

exit 0