We personally did notice this “camera hole” but didn’t give it a mention as it’s most likely the iPad’s ambient light sensor. If you recall, there was some controversy after the iPad’s announcement when people believed that the iPad Steve Job’s showed off at the keynote had an unmentioned camera, when iPad replacement parts emerged with MacBook-like camera holes, and when we revealed some camera evidence in the iPad SDK (here and here).
In the end, the camera evidence most likely was some left over code when Apple was simultaneously developing the iPhone 4 and iPad, and those “camera holes” turned out to be spots for the ambient light sensor. Because of these we held back on saying that hole is a camera. On the other hand, Apple does not normally include that ambient light sensor hole on their patents as shown here, and here. So in the end it is really a tossup. That hole could be an upcoming front-facing camera for the iPad or could simply be that ambient light sensor. We think it’s the sensor but let us know what you think in the comments.