There is a lot of grumbling out there about how the iPad and the iPhone are closed environments, and you can only run programs that are blessed by Apple, and available through the App Store.
It occurs to me that one is perfectly free to write software for your own use, simply by joining the Apple developer program. You can download the SDK and write code anytime. If you want to test the code on a real device, then you need to join the paid developer program, which currently costs $99/year.
As long as you don’t use pre-release features of the iPhone OS, you may even be able to share your source code with others. There are lots of sites out there with code examples.
So perhaps the iPhone and iPad are not closed at all, you can run Apple approved software for no extra charge, but you can run anything you write for $99/year.