Apple made several changes to the App Store Review Guidelines during WWDC this week, including an easing of the prohibition against downloading and executing code on an iOS device. The ban on executable code remains intact, but rule 2.5.2 now also provides that:

Apps designed to teach, develop, or test executable code may, in limited circumstances, download code provided that such code is not used for other purposes. Such apps must make the source code provided by the Application completely viewable and editable by the user.

The change to the guidelines is limited, but it’s an important signal to third-party developers that Apple will accept certain educational apps and developer tools on iOS, which brings the promise of app development on iOS one step closer to reality.