I\'ve written an open-source c++ application and it works fine on Windows and Linux, I finally got a Mac Mini (with 10.5.8) so I\'ve just been testing the Mac version.
Mac binaries are set to be opened with the 'Terminal' program; there's no way around that, except by making a full application package, or have another program launch it via system or something like that.
When double-clicking on a binary, the terminal window opens with ~ as the current directory. I suggest you use chdir(2) in your program to ensure it is running in the right directory if you need it in the first place.