The Omni Group posted some photos and a little story about their progress working on prototypes for the OmniGraphSketcher for the iPad. The app is a simple graph drawing and data plotting tool that they're creating an iPad version of. Apparently no one at Omni Group is sleeping much while their iPad apps are being developed, but they are doing some interesting things with hardware prototypes, including mocking up the hardware with 3d printers.
http://blog.omnigroup.com/2010/02/25/designing-omnigraphsketcher-for-the-ipad/