We do the following:
PREFIX=/usr/local
BOOST_LIBRARIES=python
PYTHON_MAJOR_VER=2.7
PYTHON_LOC=$PREFIX/python-2.7.3
./bootstrap.sh --prefix=${PREFIX} --with-libraries=${BOOST_LIBRARIES} --with-python-version=${PYTHON_MAJOR_VER} --with-python-root=${PYTHON_LOC} --with-python=${PYTHON_LOC}/bin/python
PREFIX=/usr/local
BOOST_LIBRARIES=python
PYTHON_MAJOR_VER=3.2
PYTHON_LOC=$PREFIX/python-3.2.3
./bootstrap.sh --prefix=${PREFIX} --with-libraries=${BOOST_LIBRARIES} --with-python-version=${PYTHON_MAJOR_VER} --with-python-root=${PYTHON_LOC} --with-python=${PYTHON_LOC}/bin/python