The first crop of iPad user apps revived memories of Web designs from 1993, when Mosaic first introduced the image map that made it possible for any part of any picture to become a UI element. As a result, graphic designers went wild: anything they could draw could be a UI, whether it made sense or not.
It’s the same with iPad apps: anything you can show and touch can be a UI on this device. There are no standards and no expectations.
iPad Usability: First Findings From User Testing (Jakob Nielsen’s Alertbox)
The phenomenon Jakob describes here has always been a problem with touch input. The affordances available by hovering with a mouse pointer and seeing a cursor change into a hand or seeing alt-text appear is gone in touch interfaces, and for me are sorely missed.
(via thegongshow)