With iOS's limited USB power, it can be a struggle to get your keyboard powered. Some arm-chair theorists speculate that one of the USB-Power-dongle-deals, the kind used for charging your phone in an emergency, would probably work. I've never heard of anyone actually trying it though.
Until now! Reader Maria D put theory into practice in a desperate attempt to lounge around with just her Oxygen 8 and an iPhone connected via iRig MIDI. As with any serious scientific en devour, she wisely documented her experiments.
I love her enthusiasm! I'm so glad someone finally tested this; it is great to see something like this works for iPhones or connecting bigger keyboards to the iPad! You should check out the rest of her videos. My favorite is Inside My Head; she's got huge stage pressence for such a tiny little thing!