tractiongames: not sure what might be wrong there.
Make sure you're not checking the built size of the Debug configuration, since that typically is larger.
If you are using Snow Leopard, remember that it now calculates file size with units where 1 MB = 1,000,000 bytes, instead of 1,048,576 bytes. You should do "Get Info" and get the actual number of bytes, rather than relying on the abbreviated value in the Finder window listing. Granted, this would make your app look *bigger* in the Finder, not smaller, but it's worth remembering.
Also, this method provides a worst-case number. The assumption about the binary size is based on the idea that an encrypted binary can't be compressed at all, but in the real world I'm sure it can be compressed *some*. A better method would be to actually encrypt the binary and then zip it with the resources. I'll look into that.
My games tend to be so far above the 10 MB line (and anyway I've been convinced by those who say don't worry about the 10 MB barrier) so I made this script mostly as a novelty. But I'd like to make it accurate, so please let me know what you find.