Comment #3 on issue 2208 by [email protected]: Problem running midi2ly on Mac OS X 10.6.8 : 32- vs. 64-bit code
http://code.google.com/p/lilypond/issues/detail?id=2208
Changing the shebang line in midi2ly to #!/usr/bin/env /usr/bin/arch -i386 python solves the problem for me on Snow Leopard.See http://stackoverflow.com/questions/4665818/running-python-in-32-bit-more-for-wxpython for background.
