Wil Shipley has an excellent post about the bigger picture:
The problem Mac developers are facing is that the two that Apple is enforcing on the Mac App Store (Sandboxing and Code Auditing) are implemented currently to be actively bad for developers and not particularly good for users. And the method that would provide the most benefit for developers and users (Certification) isn’t enforced broadly enough to be useful.
There are so many good paragraphs I was tempted to quote, but you should just read the whole thing.