Apparently, only damaged iPhone 5s, iPhone 6, and iPhone 6 Plus units will be accepted - folks rocking older models seem to be out of luck. It's said that a broken iPhone 5s will get you a $50 credit, while broken iPhone 6 and iPhone 6 Plus models could get you at least $200, or $250, respectively. 9to5Mac notes that this upgraded trade-in program should be launched this week (most likely, only in the US - at least for the beginning).
Another new thing that Apple started doing is to offer plastic screen protector installations in its official stores (not for free, of course). 9to5Mac reports that this is already available in select Apple Store locations, and the process is similar to what you're seeing in the video below (it's in Dutch, but you'll get the point).