Apple is still considering to allow third-party software to run on the iPhone

One additional tidbit from Apple’s shareholder meeting notes was a revealing blurb that Apple still hadn’t completely decided whether or not they will open the iPhone software to 3rd party developers.
Jobs did acknowledge that the company is still struggling to decide if third-party developers will be able to create software that will run on the iPhone. It’s a decision Apple “is wrestling with,” according to Jobs.
Apple’s choice to limit iPhone development has been the target of a lot of criticism against the iPhone. In the days after the iPhone announcement, Jobs stated that while you will be able to purchase and install additional applications on the iPhone, that this would be limited and in a “controlled environment”. As a result, the iPhone has been described as a “closed device” which could make enterprise market penetration difficult.
From Macrumors