On September 6th Apple reiterated some long standing guidelines and added a few new twists.
In order to provide users with the secure and curated experience that they expect on the App Store, we have always specified that apps must be self-contained bundles. This means that the core features and functionality of the app must be contained within the binary of the software, rather than made possible by referring users outside of the approved app, including through the use of HTML5. Apps that provide core features and functionality dynamically with web technology like HTML5 are best delivered to everyone in Safari, rather than through the curated App Store.
To prevent fraud and abuse, the exceptions to this rule have always been very narrow. In June, we updated guideline 4.7 sections 4, 5, & 6, to further narrow these exceptions and clarify an existing restriction. Apps containing or running code that is not embedded in the binary cannot provide access to real money gaming, lotteries, or charitable donations, among other changes.
You can read the full article here: App Updates for HTML5 Apps