Excellent work on the GamePad! Hopefully this will be released in such a way that commercial games can use it when present. If not, it will at least help with a WiiU emulator when the time comes.
As to the "proof" question of the hashes, think of it this way. We have a closed chest and it's heavy and no one knows what's in there. I can then say I was in there, and as proof offer this tidbit: it includes one white, globular item with a diameter of about 5 centimeters. Is that proof to anyone I've opened the chest? No. I could just be making it up. But once the chest opens, and voila, there's a giant pearl 5cm in diameter: there's my proof I was in there when I said I was.
So wait for the WiiU keys to leak and be verified genuine, perform a sha1, and compare to the slides. Match: f0f did what they said they did. It proves they had the keys at the time of posting.