The risk of government intervention seems the most likely reason to me. Better to maintain control and relax restrictions on your own terms than risk having the terms dictated to you by a judge.

Another reason, which I find more likely is the market pressure Apple is starting to feel from Android and the slew of new iPad-esque Windows 7 tablet devices coming to market soon (even Windows Mobile 7 is a threat). They need to make sure they can compete on the apps-level with the alternatives.

Is Windows Mobile 7 really a threat?

Not yet, but probably it in the future.

Microsoft may not have got Windows Mobile right in the last 10 years but they now have a good template to follow (user interface, user experience, even the business model) thanks to Apple. You can see this with Windows Mobile 7 - they've 'rebooted' and are following Apple's lead.

They're definitely the underdog but I wouldn't count them out.

Microsoft is launching Windows Phone 7 with a more restrictive development model than Apple.

The OS is just as locked-down as iOS, and as with Apple users are only allowed to install software from the official 'marketplace'; but Microsoft also restricts what license developers are allowed to release software under, and limits how many free applications they can offer without paying additional fees to MS.

The one advantage that Microsoft has traditionally had over Apple - the openness of their platforms - has been squandered.

Couple that with a featureset that is competitive with the first-edition iPhone, but nowhere matches current iOS and Android devices, and you have a recipe for a flop.

Have there been any recent developments in that respect, though? That also doesn’t do a very good job of explaining the ostensible sudden change. There would have been smoother and more effective ways of communicating that change. Any time Steve Jobs was on a stage in the last few month he could have announced that change and waxed poetically about the importance of developers for Apple.

There is a non-zero possibility that Jobs simply doesn't want to publicly admit he was wrong.

That’s certainly possible but – if true – pretty petty. Admitting you are wrong when you announce a policy change seems like a great move to me, at least when you are in a position of strength like Apple undoubtedly is at the moment. (Depending on your goals you might not want to admit to making mistakes when you are in a weak position so as to not seem desperate.)

Steve Jobs is never wrong. Sometimes the universe is wrong, and he has to compromise, albeit grudgingly and with bad grace.

I think it's just a byproduct of a maturing platform. Apple has nurtured the platform into a certain direction and more or less set a standard for what an iOS app is going to be. (look & feel, stability, security, etc) Now that users also have high expectations the App Store is probably starting to police itself to some degree. I'm guessing they reached a point where only 1-2% of apps had any approval issues so it's becoming more practical to switch to an innocent until proven guilty model.

I feel like this is exactly how Apple responded to the whole iPhone 4 antenna problem: by not really mentioning it, acting as if there were no big issues, and then silently providing a fix. There seems to be a pattern here.

Having a press conference is not exactly "silently".

The really amusing thing to come out of the whole 'antennae-gate' issue was Apple's messages: when launching the iPhone 4, it was revolutionary (again), but when problems emerge, it's just like every other smartphone. Cracks in the reality distortion field, methinks.

This really doesn't indicate any policy change, as apps with similar functionality have been approved for a long time now.