Well Apple will reject:
* apps that download additional standalone code - a security risk
* apps that have kext (ie kernel drivers) - this is a security risk anyway so I agree.
* apps must use the apple store to provide updates - a bit meh, but I can see that they can replace the binary with something that then references the developer store thus cutting out apple from the money.
* apps that offes a application plugin 'store' (ie for adding functionality) via a non-apple store. (this doesn't prevent app developers from selling the plug in separately then allowing the user to drop the plugin into the purchased app - I wonder how quick that will be blocked through the t&c).
There is no exclusivity clause in the t&c although the legal contract has a second portion for charged apps..