Woot, I finally got it working on OS X (10.8.2).
1) The Allegro library symbolic links from the dfhack archive were broken and needed to be relinked. I did build new Allegro libs, but at the end just relinked the original dylibs from the archive. This is for the Dwarf Builder distribution, with manually installed dfhack, so adjust your paths accordingly.
cd /Applications/DwarfBuilder.03411v14/DwarfFortress.app/Contents/Resources/stonesense/deplibs
ln -sf liballegro.5.0.7.dylib liballegro.5.0.dylib
ln -sf liballegro_acodec.5.0.7.dylib liballegro_acodec.5.0.dylib
ln -sf liballegro_audio.5.0.7.dylib liballegro_audio.5.0.dylib
ln -sf liballegro_color.5.0.7.dylib liballegro_color.5.0.dylib
ln -sf liballegro_dialog.5.0.7.dylib liballegro_dialog.5.0.dylib
ln -sf liballegro_font.5.0.7.dylib liballegro_font.5.0.dylib
ln -sf liballegro_image.5.0.7.dylib liballegro_image.5.0.7.dylib
ln -sf liballegro_main.5.0.7.dylib liballegro_main.5.0.dylib
ln -sf liballegro_memfile.5.0.7.dylib liballegro_memfile.5.0.dylib
ln -sf liballegro_physfs.5.0.7.dylib liballegro_physfs.5.0.dylib
ln -sf liballegro_primitives.5.0.7.dylib liballegro_primitives.5.0.dylib
ln -sf liballegro_ttf.5.0.7.dylib liballegro_ttf.5.0.dylib
ln -sf libfreetype.6.dylib libfreetype.dylib
ln -sf liballegro_image.5.0.7.dylib liballegro_image.5.0.dylib
2) It is very likely some other libs will not be i386 compatible, so you will need to upgrade those to universal. Start dfhack, if it reports it cannot start stonesense plugin, check the stderr.log, search for "stone". You will see the library that didn't get loaded (with the full path). You will need to update this lib using MacPorts (follow this guide here to install MacPorts and upgrade libs
http://wiki.allegro.cc/index.php?title=Install_Allegro5_From_SVN/OSX).
I needed to upgrade only the following libs (though I did follow the Allegro guide completely before it):
sudo port upgrade --enforce-variants physfs +universal
sudo port upgrade --enforce-variants freetype +universal
3) Optional: If you want to build your own Allegro libraries, use the following to build i386 compatible (i.e. 32 bit ones), instead of just "cmake ..". Follow the above guide in all other steps (though you may want to use "make -j4" for faster build, substite 4 for the number of cores you have):
cmake .. -DCMAKE_OSX_ARCHITECTURES="i386;x86_64"
This will produce both 32 and 64 bit compatible libs which should work with stonesense. You'd still need to link or copy them to stonesense/deplibs/.