If you've been submitting applications to the Mac App Store, you've probably seen errors about files or your App having Invalid Signatures. The solution is to use codesign to fix this. As of this pull request https://github.com/MacRuby/MacRuby/pull/52#issuecomment-3745546, macruby_deploy now fixes this with a --codesign switch that requires the name of your signing certificate. Hopefully this saves some people a little greif. Daniel