Apple has a very tight control over what goes into their app store with what gets turned into an app and this does have some good reasons behind it. Controlling the content that is not copy written; make sure the app enhances the iPhone experience not just re-skin what the iPhone already does. Also this should control apps that are not worth their weight being sold for too much. But what this also seems create instead is a centralized decision of what apps are acceptable, what apps may hurt the Apple / AT&T profit margin, and what apps may cause competition with what apple has created or charges for.
Theoretically you could sell products through your own site to make more profit through your iPhone application. However, if those products are available through the Apple iTunes store (music, albums, movies, possibly games), than chances are that this application will never make it past the development stage. Apple will want a piece of the pie for you to sell products through the iPhone even if it makes a better user experience or cheaper for the user to buy it through your site. While this is probably not a monopoly it does have similar qualities of a monopoly. Discrimination against competition in the same market, through their device in this case, by having complete control over what goes on the iPhone and the ability to discourage improvements that may hurt the overall profit margin of the product or provide a service that is less expensive.
The largest app that this is sparking a lot of controversy is the Google Voice Application (a powerful service which lets you receive calls from a different number and even send free text messages). Granted this would probably hurt Apple / AT&T’s profit margin but it’s sparked even the interest of the US FCC to investigate the approval process by Apple and AT&T. This is still being investigated, and the application is not completely rejected yet, it does not shine a good light on the app approval process which could cause allot of changes to the app approval process by Apple.
In my opinion these acceptance processes don’t make a lot of sense, beyond a business money making view. Maybe all of this strategic planning is why it can take anywhere from a week to a month and half (based on my personal experience) to get applications launched onto the app store. Another theory is that Steve Jobs is checking each app individually for 'Quality'. Who knows what really goes on, but whatever the process is it will be interesting to see how the cards fall after the FCC, Google, Apple, and AT&T controversy is over.