In addition to the $99 licensing charge to distribute the application (whether it's a free or commercial app) companies seeking a proprietary solution will need to cough up another $200 ($299 total) for the 'Enterprise Programme'.
Another item worthy of note those still using PowerPC machines: if you want to develop for iPhone, you'll not only need Leopard, but an Intel-based Mac to run the SDK. Disagreements about architectures aside, what does your $99 get you?
- Complete set of resources in the iPhone Dev Center
- Testing of your code on iPhone and iPod touch
- Code-level technical support from Apple engineers
- the ability to reach every user via the Application Store