So, here's an update. I noticed something interesting in the GDB logs: http://pastie.org/3772361
This happens when SDL.framework is located in both /Library/Frameworks and the application bundle.
If I remove SDL.framework from /Library/Frameworks, the game refuses to open, OS X complaining that the game's not compatible etc etc.
If I remove SDL.framework from the application bundle... the game runs! Until it crashes at Crypto++, anyway (keep in mind that's a statically linked library, not a framework, as that's all I could find for it on OS X).
EDIT: I've narrowed the problem child down to just SDL.framework... the SDL_* frameworks all work just fine.
EDIT 2: Manage to fix Crypto++. So, now all we have to do is get SDL.framework to play nice...