I've been having this problem where an app built with py2app does not run correctly when I double click it from Finder. It works if I run the executable directly (.app/Contents/MacOS/app) from Finder or via terminal.
I tried troubleshooting but only got so far as to know that applicationDidFinishLaunch: is not getting called on my app delegate. I dont know why though.
I found a couple other threads talking about the same problem -
I'm using py2app v0.7.1, pyobjc-core v2.4 on OS X 10.8.2.
Hope someone here can help!