Apple first introduced in-app purchasing with the release of iOS 3. The company takes the same 30% cut from in-app purchases that it does from standalone app sales. More recently, the company has suggested that apps offering digital content for purchase outside the App Store must also offer that content via in-app purchasing, with a June 30, 2011 deadline for compliance. That impending deadline makes the timing of the legal notices all the more interesting.
Should Apple not offer legal assistance in some form to threatened developers, it's possible those developers may end up needing to leave the App Store, or at least changing their approach to it. As Thomson tweeted, "A decent [Intellectual Property] lawyer will burn all the profits from PCalc in-app purchasing in one day." Thomson is also delaying the release of PCalc 2.4 until he knows more about his current legal situation.
Since Apple takes pride in the size and breadth of the App Store, it's not unreasonable to assume that the company will offer developers some assistance. Whether that would take the form of direct legal aid, legal action against the company alleging patent infringement, or something else entirely, remains to be seen.