I am not an IP attorney so I rarely comment here on litigation (threatened or otherwise) involving patents, but this one is worth mentioning because it may be of interest to many of you even if, like me, you don't have a deep knowledge of patent law. The central company in this story is Lodsys, a patent holding company that currently owns U.S. Patent No. 7,222,078, a patent that concerns a system in which "information is received at a central location from different units of commodity" and the "interactions elicit from respective users their perceptions of the commodity." You can read the full patent here.
Almost two weeks ago, Lodsys sent letters to iPhone app developers who use the in-app purchase system asserting that the developers violated this patent. Apple has a license on the patent, and Lodsys asserted that any developer using in-app purchases also needs to obtain a license. Many developers were worried that they lacked the resources to litigate over this patent.
Yesterday, Apple sent a three page letter to Lodsys asserting that Lodsys had no basis to make its claims against the app developers. One of Apple's primary arguments is that app developers are using an Apple system, and Apple already has a license for the patent, so app developers don't need their own license. As the letter says in the first paragraph: "Apple is undisputedly licensed to these patent[s] and the Apple App Makers are protected by that license." You can read Apple's full letter here.
For more details about this story, I recommend that you read this analysis by Chicago attorney Nilay Patel (which was written before Apple responded) and this report by Lex Friedman of Macworld which was written after Apple sent the letter.