Apple apparently chose the best possible template for its iPhone developer programs: its own Apple Developer Connection for OS X. Why it then made the iPhone SDK confidential even for those who download it for free poses a puzzling contradiction in the company's seemingly open approach to development.
The basic ADC membership is open to everyone and free of charge. All you need is a verifiable (at least temporarily) e-mail address to obtain a free Apple ID. Free and paying ADC members get exactly the same commercial-grade development tools, samples, and docs. Depending on their membership level, paying members get additional access to pre-release software, prepaid tech support incidents, hardware discounts, and WWDC tickets. Free members face no disadvantages when it comes to creating and distributing applications for the current or prior release of OS X. That cornerstone of the Mac platform accounts for its large catalog of high-quality free and inexpensive applications, as well as its loyal and welcoming community of developers. ADC is the magnet that draws developers to the Mac from other platforms.
By choosing ADC's tiered programs as a model, it seemed that Apple had tilled the field for an instant and vibrant iPhone dev community. Then it salted the ground by making the iPhone SDK confidential even for those who download it for free. The upshot is that every citizen of planet earth can get the iPhone SDK at no charge, but they're contractually obligated to Apple not to discuss the SDK or exchange ideas with others. The agreements leave no room for forums, newsgroups, open source projects, tutorials, magazine articles, users' groups, or books.
The terms and conditions of the most restrictive Agreements to which all iPhone developers are bound are secret. A few sentences from the nonconfidential iPhone Registered Developer Agreement (PDF) are sufficient to illustrate the breadth and severity of the restrictions. As is always the case, you must not rely on my excerpts or analysis as a summary of the Agreement or as legal advice.
From Section 3, Confidentiality: "You agree not to disclose, publish, or disseminate any Confidential Information to anyone other than to other Registered iPhone Developers who are employees and contractors working for the same entity as you and then only to the extent that Apple does not otherwise prohibit such disclosure in this Agreement."
What's "Confidential Information"? The Agreement contains two definitions, one in Section 3 that's broad and rambling but with specific and liberal exceptions, and one in Section 4 that's concise and inescapable:
From Section 4, iPhone Materials: "All iPhone Materials shall be considered the Confidential Information of Apple"
Section 4 also makes unrestricted allowance for additional tightening of screws (not quoted in full): "All use of the iPhone Materials shall be subject to this Agreement, unless such iPhone Materials are accompanied by a separate license agreement, notice or disclaimer (collectively, "Other Agreement") in which case such Other Agreement will govern to the extent of any inconsistencies with this Agreement [...]"