The lead developer behind the Mac dock replacement DragThing and the iOS scientific calculator app pCalc is about to be sued for patent infringement because his software uses Apple’s own in-app purchasing mechanism, reports "Cult of Mac" (http://macte.ch/RAJ1E). The company who filed the lawsuit claims that the developer's use -- and that of others -- of Apple’s in-app purchase system violates a patent it owns.

Developer James Thomson of TLA Systems first broke the news that the latest version of PCalc would be delayed due to the threat of a lawsuit Friday morning on his Twitter feed. Thomson -- who hasn't named the company suing him -- is currently working with Apple as a first step to knowing how to address the issue, says "Cult of Mac." The company suing him wants a "hefty" licensing fee.

Not only will the lawsuit delay the latest update to the free version of pCalc, pCalc Lite, it may just be the opening shot in an IP war, not just against Apple, but against the developers who sell their software on the App Store, says "Cult of Mac."

What's more, Patrick McCarron, a developer for MobileAge (the company behind Shanghai Mahjong and other apps), says he's also been hit with a threatening patent lawsuit over his use of Apple’s in-app purchasing mechanism.

Apple first introduced in-app purchasing in 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.

Apple hadn't yet publicly responded to the lawsuits. What's strange in the case is that the suing party is targeting small developers, not Apple itself.

-- Dennis Sellers