You can't release it for a different platform you have to recreate it because of different APIs, programming languages, platform capabilities, SDKs etc. With a book, you just send the MS elsewhere or at worst, print it out again.
That's what I meant by there are holes in the analogy and it doesn't really work. My point was that just as you are free to seek a different publisher, you are also free to seek another platform - the holes being that the app would have to be re-developed. Technically another option would be to release to the jailbreak community but I really don't know how that works (for revenue, hosting of the application, etc) and it's a less than ideal solution.