According to The Loop, Apple has sent a letter to patent holder Lodsys, asking them to stop threatening iOS developers with patent infringement letters.

“Apple is undisputedly licensed to these patents and the App Makers are protected by that license,” wrote Bruce Sewell, Apple Senior Vice President and General Counsel.

Good for Apple. More as this develops.

UPDATE: Macworld has the full text of Apple's response letter. Here are some good bits. [Macworld]

Because I believe that your letters are based on a fundamental misapprehension regarding Apple’s license and the way Apple’s products work, I expect that the additional information set out below will be sufficient for you to withdraw your outstanding threats to the App Makers and cease and desist from any further threats to Apple’s customers and partners.

Through its threatened infringement claims against users of Apple’s licensed technology, Lodsys is invoking patent law to control the post-sale use of these licensed products and methods. Because Lodsys’s threats are based on the purchase or use of Apple products and services licensed under the Agreement, and because those Apple products and services, under the reading articulated in your letters, entirely or substantially embody each of Lodsys’s patents, Lodsys’s threatened claims are barred by the doctrines of patent exhaustion and first sale. As the Supreme Court has made clear, “[t]he authorized sale of an article that substantially embodies a patent exhausts the patent holder’s rights and prevents the patent holder from invoking patent law to control postsale use of the article.” Quanta Computer, Inc. v. LG Elecs., Inc., 553 U.S. 617 (2008).

Therefore, Apple requests that Lodsys immediately withdraw all notice letters sent to Apple App Makers and cease its false assertions that the App Makers’ use of licensed Apple products and services in any way constitute infringement of any Lodsys patent.

UPDATE 2: FOSS Patents weighs in with Florian Mueller's analysis [FOSS Patents]

I don't mean to be negative here. I just want to make all app developers fully aware of the issues they may still face. Since Lodsys is already suing a group of large players, which is collectively even more powerful than Apple, it would be irresponsibly optimistic to assume that Apple's letter all by itself is going to make Lodsys give up. Unless Apple settles the deal with Lodsys (neither the terms of such a deal nor the mere fact might ever be announced -- Lodsys might simply never follow up on its original infringement assertions), there will be some next step in this process, and things could still get nasty. So let's be optimistic today, but let's also be cautious.

UPDATE 3: Nilay Patel offers his thoughts as well [This is my Next]

The big question now is whether Lodsys is willing to take Apple to court in order to challenge that license interpretation; Lodsys would be fairly foolish to have not considered exactly this situation when they formulated their business plan. We’ll see what happens, but for the moment things have taken a promising turn.