There's no doubt that Apple for the first time in iOS history is opening up its mobile operating system by giving developers the tools to create previously unheard-of features like custom iOS 8 keyboards, new filters for the Photos app, custom Share sheet actions and several other types of App Extensions.
It would also appear that Apple is testing a feature that would allow end users to choose alternate looks for the iOS 8 user interface with different font types, custom color schemes and more.
This could be a huge boon to tinkerers and a great selling point because never before has Apple allowed people to customize the iOS look and feel without jailbreaking their devices...