The author, and anyone else interested in exploring Mach-O files, might want to check out the otool command on Mac OS X. The otool source code is open source: http://www.opensource.apple.com/source/cctools/cctools-870/o...

someone made a mach-o lib for ruby: https://github.com/woodruffw/ruby-macho

You might dig this Alex:

https://github.com/cebix/macemu/blob/master/BasiliskII/src/U...

Many years ago, I wrote something about Universal Binaries - http://hohle.net/scrap_post.php?post=197 . IIRC, they've remained relatively unchanged since NeXTSTEP and have always been available in OS X (and even used during the G3/G4/G5 era in Mac OS).

Related: https://github.com/shinh/maloader is a loader for running mach-o files on Linux.