I'm sorry, I didn't understand your problem the first time.
In fact, it's not a Mac App Store problem, but a Gatekeeper problem. Apparently, Apple has enabled Gatekeeper on Mac OSX 10.7.4, and there's not even a way to disable it, as it doesn't appear as it should in the security options.http://help.fuelcollective.com/discussions/problems/2857-cannot-run-pochade
To fix the problem, I've signed the program with my developper signature. Please download the program again, and it should work.
The bad new is that I dropped Snow Leopard support
1) I need to use XCode 4 to compile a Gatekeeper signed version of the program.
2) when I set XCode 4 to make the program compatible with Snow Leopard, that compiles fine, but that doesn't work as it should (just one of the million bugs of XCode).