The Guidelines are only available to registered iPhone developers and require a login, but here are some of the broader themes:
Most surprisingly, Apple is changing a policy that it adopted in April 2010 as part of the iPhone OS 4.0 beta SDK. The controversial old section 3.3.1 of the iPhone Developer Program License Agreement read:
3.3.1 — Applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs. Applications must be originally written in Objective-C, C, C++, or JavaScript as executed by the iPhone OS WebKit engine, and only code written in C, C++, and Objective-C may compile and directly link against the Documented APIs (e.g., Applications that link to Documented APIs through an intermediary translation or compatibility layer or tool are prohibited).
iOS Developer Program License Agreement sections 3.3.1, 3.3.2 and 3.3.9 relax these restrictions:
In particular, we are relaxing all restrictions on the development tools used to create iOS apps, as long as the resulting apps do not download any code. This should give developers the flexibility they want, while preserving the security we need.
The new section 3.3.1 of the updated agreement now reads:
3.3.1Applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs.
The updated agreement no longer bans specific programming languages and “intermediary translation or compatibility layers" -- which would appear to re-allow the use of tools like Adobe’s Flash cross-compiler -- provided that the app doesn't download or install executable code.
This is the new section 3.3.2:
3.3.2 An Application may not download or install executable code. Interpreted code may only be used in an Application if all scripts, code and interpreters are packaged in the Application and not downloaded. The only exception to the foregoing is scripts and code downloaded and run by Apple’s built-in WebKit framework.
Kudos to Apple for taking a major step toward transparency in the App Store, it's a positive step in the right direction -- but more importantly it means that Apple is listening to its developers.