I sincerely don't think that it's a stunt by Apple, and to claim that it is would require a fairly myopic view of the state of software patents today.
That said, the "conspiracy theory" falls apart because this is ultimately self-serving by Apple; in-app purchases translate to money for them, and if developers are too scared to include content purchasing options in their apps (since in-app is the only permitted method, natch), it means a direct hit to Apple's bottom line. It isn't altruistic towards developers, so it's silly to see it as a justification of Apple's 30% cut.
Apple Exec: People are pissed about the 30% in-app thing, what should we do?
Other Apple Exec: Add value to it.
Apple Exec: How do we do that?
Other Apple Exec: Show people that if they didn't use our methods and lose their 30%, they'll get sued for licensing fees for an in-app purchasing patent and probably lose it anyways.
Apple Exec: "Hey Lodsys, we're already paying you money, but could you do us a favor real quick..."
I'm not claiming this is what happened, because I sincerely don't think it is what went down. I'm just illustrating a theoretical and likely fictional path.
But...the problem is that developers are getting sued for the thing they were pissed about before, so now they're just double-pissed. It's not like they're getting sued for using some alternative that saves them 30% on purchases.
0.5% doesn't seem much, but if they succeed in this, many more other patent trolls will come out of the woodwork and all will demand a small percentages. Lots of these quickly add up, with 100 patent trolls parasiting on your App, you lose already half the profit.
That said, the "conspiracy theory" falls apart because this is ultimately self-serving by Apple; in-app purchases translate to money for them, and if developers are too scared to include content purchasing options in their apps (since in-app is the only permitted method, natch), it means a direct hit to Apple's bottom line. It isn't altruistic towards developers, so it's silly to see it as a justification of Apple's 30% cut.