The likely candidates are Retinal Scan screen which Jobs probably wanted with the original iPad, but could not get. More memory, which is typical. They may drop the 16GB to a wifi only model, and then go to 128GB max. A faster processor is likely, as is a forward facing camera. With the slot already allocated, and the new FaceTime, the camera is almost a given. Also expect a couple of new add-on devices to become available. The gyroscope would be an easy addition, so we should see that too.