Just saw this on Cult of Mac. I tried it out and sure enough, the split keyboard on iPad iOS5 has invisible keys that you can tap in case you forget where the actual keys are. This is similar to the microphone button on iPhone 4S behaving as a space key if you are typing away and miss the shrunken space key. If you are typing and you tap quickly to the left of H key in split-keyboard, you get the G key. Same thing on the opposite side if you tap to the right of the G key (similar behavior for T/Y keys and V/B keys). This is fairly ingenious and I think Apple should patent this -- I can't imagine many folks thinking of doing stuff like this to best-guess typing on a touchscreen keyboard.