Interesting read, thanks. I like the humor in the open letter.
This is worth knowing about all iPad apps:
The hitch is due to the restrictions Apple places on third-party apps for the iPad (in the iPhone OS), namely that the apps don't have direct file access to the photos on the flash card, or any files outside of the app's "sandbox" for that matter. On the iPad the photos must first be imported into the "photo library" using the built-in "Photos" app. Then you could presumably switch to a third-party app to browse your photo library and do your work. But right now it is impossible to create an app that works directly with the original photos (or movies etc) on a flash card. Everything must start and go through the built-in "Photos" app.
It kind of gives us an indication of how useful or useless the iPad can every really be for photography related stuff. The 'hows' and 'whys' are explained in more detail in the open letter.