Not only "not sanctioned" by Apple, but actively opposed by them. They go out of their way to stop jailbreakers and consider them criminals, and per the DMCA they're probably right. It will be terrible for future innovation if the only way to gain control over your own hardware is to become a felon.

Of course they don't like people jailbreaking, they've worked very long and hard on making a store with a fair and seamless DRM system - then barely a week after it's jailbroken somebody has gone and made an almost one-step process for cracking, distributing and downloading pirated applications. DRM relies on a closed system by it's very nature - it's understandable they like to discourage against subjugating their entire business model.

HOWEVER: they have never (as of my knowlege) put in additional effort to prevent jailbreaking. The online media a few years ago was buzzing with warnings about updates bricking jailbroken iPhones - like if done out of some sort of malice when it turns out the problem was AnySIM completely trashing some areas of the baseband, rendering it unusable when updated next.

So let's see, Apple getting a ton of bad press misdirected at them (as usual) because of the clumsy mistakes of some people who didn't really test their baseband modifying software before releasing it to the public.

Oh, and a more recent example. The installer for OpenSSH in Cydia didn't bother to prompt a change for the default root password on the iPhone (alpine) - suddenly there's a "virus" spreading between unsecured jailbroken iPhones because of clueless idiots once again thinking they know what they're doing when they clearly don't. The press? "OMG ITS TEH IPHONE VIRUSSSSS RUN FOR THE HILLS!!" Do you think they bothered to mention that you had to a) Jailbreak your phone, b) Install OpenSSH and c) Neglect to change the default password? Of course not, who cares insignificant details like that when you can have a headline with the words "iPhone" and "virus" both in it.

Gee, I wonder why Apple don't like jailbreaking guys?

Meanwhile, it would be naîve to think that Apple doesn't have plenty of jailbroken iPhones they use internally for various things. I have no doubt they are keeping a very close eye on the progress of the JB scene.

Along with anything that remotely competes with Apple's business model. If Microsoft had that level of control 20 years ago, we wouldn't have the web.

We don't know the exact reason for many Apple's rejections, but I disagree with this sentiment in general - there are hundreds of examples of approved apps which directly with Apple's own offerings and if you're referring to the GV rejection in particular that's even more puzzling as it doesn't compete with Apple at all (unless they're secretly planning on becoming a telco?) Examples of approved apps which might enroach on Apple's territory are various Safari replacements (iCab etc), Map applications, and even Spotify; clearly stepping on the toes of iTunes store. The problem is the inconsistency, which to me points more toward individual agent whims or moods rather than policy. I agree this is unacceptable but they have promised to make it better. They have stated publicly that they approve > 99% of apps, so as usual it's a vocal minority.

That's a testable prediction, since Android offers exactly that setting. We'll see if it becomes a cesspool of malware; I don't expect it to.

There has already been a bank account phishing app which was undiscovered for weeks on the Android Marketplace. I wonder why whoever coded that didn't target the iPhone instead and get 100x the opportunity?

Oh that's right, they couldn't. The system works.