Apple announced today an upgrade to their new iPad which was announced only 6 months ago. It is very unlike Apple to release an upgrade only 6 months after the last. I'm guessing it's just to keep up with current tech.
The new iPad now has an A6X chip which will put it up there with the iPhone 5, Apple say it is twice as fast. It also now has the lightning dock connector. Other than that there are no other major upgrades. It still has the retina display, same cameras an same battery life. It's a very minor upgrade but Apple are still calling it the 4th generation model.
The prices remain the same as the 3rd generation, starting at £399.