If you have upgraded to the MacPython binary off python.org and rebuilt your boost libs from source (to match your new python version) you may encounter the "Fatal Python error: Interpreter not initialized (version mismatch?)" error.
python-selecttool to switch your default version of python to the Macports version, then rebuild mapnik using that python. When installing a version of python with macports, it should output this hint:
---> Activating python25 @2.5.4_0+darwin_9+macosx
To fully complete your installation and make python 2.5 the default, please run
sudo port install python_select sudo python_select python25
The scenario goes as follows...
$ sudo python scons/scons.py TIFF_INCLUDES=/usr/local/include JPEG_LIBS=/opt/local/lib JPEG_INCLUDES=/opt/local/include DEBUG=y BOOST_LIBS=/usr/local/lib BOOST_INCLUDES=/usr/local/include/boost-1_35
Mapnik will build just fine with your new python installation will not complain but when importing you get the "Fatal Python error: Interpreter not initialized (version mismatch?)". Check to see what your _mapnik.so is linking against.
$ cd ~/src/mapnik springmeyer:mapnik spring$ otool -L bindings/python/_mapnik.so | grep python bindings/python/_mapnik.so: /opt/local/lib/libboost_python-mt-1_35.dylib (compatibility version 0.0.0, current version 0.0.0)
If, like the above command result, you see that your mapnik module it linked against 'opt' (the macports dir), then either remove boost from macports or switch to the macports version of python. Even if you pointed the SCons path variables at a different version of boost, the SCons linker found the macports version because it was on the library path of another one of your dependencies (In the above example, the JPEG_LIBS).
The easiest solution is to uninstall boost from macports:
$ sudo port uninstall boost
Also, make sure you do not have multiple installations of mapnik in several different site-packages locations.
locate _mapnik.so # should turn up only on install location
When you rebuild mapnik after uinstalling boost, mapnik will overwrite previous problematic libraries that were linked against the wrong version of boost, but only in the one place mapnik gets installed. So, hand remove any duplicated install locations.
Finally, follow the boost build instructions at MacInstallation and link up your boost libs. On leopard as of r738 the links in /usr/local/lib are:
$ sudo ln -s libboost_system-mt-1_35.dylib libboost_system-mt.dylib $ sudo ln -s libboost_filesystem-mt-1_35.dylib libboost_filesystem-mt.dylib $ sudo ln -s libboost_regex-mt-1_35.dylib libboost_regex-mt.dylib $ sudo ln -s libboost_iostreams-mt-1_35.dylib libboost_iostreams-mt.dylib $ sudo ln -s libboost_program_options-mt-1_35.dylib libboost_program_options-mt.dylib $ sudo ln -s libboost_thread-mt-1_35.dylib libboost_thread-mt.dylib $ sudo ln -s libboost_python-mt-1_35.dylib libboost_python-mt.dylib
From here you should be able to rebuild, reinstall and run mapnik from the interpreter without a problem.