Part of the US antitrust settlement with Microsoft required Microsoft to disclose private APIs used in middleware and to document protocols used by its software

Part of the US antitrust settlement with Microsoft required Microsoft to disclose private APIs used in middleware and to document protocols used by its software. iBooks uses private APIs (especially in WebCore and WebKit), which Apple specifically prohibits 3rd party developers from using. These alone provide Apple with an unfair advantage in user experience. Additionally, Apple ships an in-app store in iBooks, which both their ToC and technical limitations of in-app purchase API make impossible for 3rd party developers to implement in their own apps. So, no, Apple is not on equal ground and at this point, I don't see how Apple can hope to avoid litigation on the issue.