I read this article about using the iPad 2 Smart Cover as a study aid. My first thought as an iPad user was "cool!" My second thought as a UI designer was "stupid!" Let me count the ways.
1. Doesn't work in portrait orientation.
2. Easier to swipe up with one finger (or tap a button) to reveal answer vs. flipping the Smart Cover.
3. In iOS5, using this app with the Smart Cover will cover up notifications.
4. Useless feature for those who do not use a Smart Cover.
I'm all for pushing the envelope when it comes to UX. But this isn't one of those examples -- it's just a marketing gimmick to get some free press.
So let this be a "Jurassic Park" lesson for you aspiring UX/UI kids: Just because you can do it doesn't mean you should.