According to certain device management vendors, Apple, without an explanation of any kind, has dropped its own jailbreak detection API from iOS no less than six months after releasing it. The reasons behind this decision are a mystery, as Apple has declined to comment on the decision to abandon the API in the release of iOS 4.2.1.
Apple's API let MDM (Master Data Management) applications access core information about the version of iOS running on any given device. Basically, the jailbreak detection API allowed certain applications to ask an iOS system if it had been compromised. Surprisingly, in the newly released iOS 4.2.1, that API is nowhere to be seen...