My question on UXExchange regarding window control positioning and arrangement started a discussion on how physical ergonomics should be considered when designing those controls. Perhaps, this issue would be a lot more relevant for touchscreen devices. Furthermore, window controls aren't the only elements that should be considered when talking about the physical ergonomics of interacting with a GUI.
The form factor of devices, screen size of devices, handedness of people, and effort required to hold the device are some of the factors that could affect the interaction of fingers of people and touchscreen interfaces.
The world should prepare to face a finger-friendly internet. The spotlight starting to move away from the mouse.