With regard to what seems to be a OS limit on file size, I think I’ve figured out why. The iPad utilizes a version (v3.2) of the operating system designed primarily for the iPhone (currently v3.1.2). The maximum image size limit is the same as the resolution of the camera in the iPhone 3GS. If they are indeed tied (the iPhone OS is hardcoded to be limited to the resolution of the embedded iPhone camera), this is both good and bad news. Considering that the upcoming iPhone 4G will most likely have a better camera (8MP according to current rumors), then with v4 of the OS I should be able to edit larger image files. The problem is that there will still be a hard limit smaller then the image files I wasn’t to edit (8MP versus 12MP).
Oh, well. Here are some more studio photos edited on the iPad, then uploaded into my Flickr photostream using their free iPhone app, because they don’t have an iPad version yet.