After a quick read of the iOS developer agreement, it doesn't appear that Apple has any obligations in this matter, rather it appears that the application developers are required to pay for the defense of Apple due to their "(vi) [Your] use of the Apple Software or services, Your Application, Licensed Application Information, metadata, Registered Devices, or Your development and distribution of any Application." (See Section 11 - Indemnification). Depending on what Apple decides to do this could get interesting.
Apple should immediately amend their agreement to indemnify all developers against patent lawsuits stemming the required use of their APIs. Otherwise, some developer will cave and pay these guys off which will start a cascade of additional lawsuits. Additionally, no one should think this is an iOS only problem. If the patent applies to iOS in app purchases it will apply to Android as well.