What kind of package size are we talking here? I see MacRuby is 30MB, surely the whole thing isnot required.
I cobbled together a process using information found on a number of blog posts and mailing list archives which let me exclude the parts of the stdlib I wasn't using. This got the file size down to 14MB. However, I don't have any QA resources so I'm not sure if this has introduced any instability in the app.
In contrast, the pure Cocoa version of this app is 4.5MB.