Allowing only App-Store-signed apps on the Mac would be suicide for Apple. They know this. It wouldn't happen, and if it does happen, then it would mean the end of the platform. Techies only have locked-down iPhones and iPads because they can still run any open-source or third-party tools they want, wether to write their own programs or just create content like websites, or play indie games, etc..
It just won't happen. If anybody was going to do this on the desktop already, it would be Microsoft, and they've already made it clear that "trusted computing" is just a feature along side that all-important cornerstone of computing: running whatever the flip you want.
It just won't happen. If anybody was going to do this on the desktop already, it would be Microsoft, and they've already made it clear that "trusted computing" is just a feature along side that all-important cornerstone of computing: running whatever the flip you want.