Sarah Sampsel wrote about designing the Washington Post iPad app, in 2 entries describing a little bit about the process. The first entry describes the types of interaction, visual design, and brand issues she had to consider when designing for the device. The second shows a few wireframes of the evolution of the home screen design.
Would have been lovely to also see some of the sketches, but it's awesome that Sarah shared not just final wireframes, but a series of wireframes showing the iterations. I'm hopeful that she'll continue the series to discuss the visual design and some post-launch thoughts.