Last week NetworkWorld reported that Apple has quietly disabled the jailbreak detection API in iOS 4.2 less than six months after introducing it. Nobody really knows why they did it:
Device management vendors say the reasons for the decision are a mystery, but insist they can use alternatives to discover if an iPhone, iPod touch or iPad has been modified so they can load and modify applications outside of Apple’s iTunes-based App Store.
You can read the full article here.