iOS developers being threatened with in-app purchase patent infringement?

Developer James Thomson reported on Twitter this morning that he's been threatened with patent infringement for his use of in-app purchases in PCalc Lite.

Just got hit by very worrying threat of patent infringement lawsuit for using in-app purchase in PCalc Lite. Legal docs arrived via fedex.

No idea what to do... They seem to be effectively claiming the rights to in-app purchase, but going after me, not Apple.

Talking to Apple now, may go quiet on this for the short term until I know what's happening.

So, have talked to Apple contact - currently scanning everything in to send. Sorry folks, no PCalc 2.4 happening today.

To be clear, I haven't been sued yet - I've been told that I am infringing their patent, they want me to license it, and I have 21 days.

Thomson isn't the lone target of these threats, his UK timezone might just have gotten them to him sooner. Already Patrick McCarron has reported the same thing.

Anyone else get a patent threat via FedEx for in-app purchase use in their iOS app? So far @jamesthomson and I got hit.

I can now check off being threatened by a patent troll off my bucket list.

There are likely other developers who simply haven't chosen to come forward yet. If you've gotten a FedEx patent threat today, let us know.

UPDATE: The company claiming infringement is Lodsys and they seem to be targeting iOS apps that have free/lite versions and full versions, and link to or allow updating within app from free/lite to full. Rob Gloess of Computer LogicX was hit yesterday [MacRumors]

Our app, Mix & Mash, has the common model of a limited free, lite, version and a full version that contains all the features. We were told that the button that users click on to upgrade the app, or rather link to the full version on the app store was in breach of US patent no 7222078, we couldn't believe it, the upgrade button!?!

UPDATE 2: Apparently, according to the iOS SDK license, developers are not allowed to settle these kinds of lawsuits. [TidBITS]

[@jamestomson, @McCarron]