Apple iOS 4.2 has secretly and silently removed the API used for jailbreak detection. This change has been made without any notice from Apple. The jailbreak detection feature introduced in iOS 4.0 was used to detect if there was any tampering with iOS. However, vendors dealing in Device Management have claimed that they have methods to detect tampering when it was becoming hard for Apple to keep their codes updated with the jailbreak methods.
Put simply, third party vendors pwned Apples jailbreak detection API. The purpose of both the API and vendor codes is to detect jailbreaking and prevent users from using features like corporate mail servers.
The primary reason behind Apple pulling the switch on this API was that it was not in use by any of the vendors and it could not keep up with the jailbreaks.
Android on the other hand has rooting as an important aspect and has some apps that specifically require and encourage rooting. This offers a considerable freedom from Google in that it does not go to some great lengths to detect rooted devices so that some apps can block their access. The Android ecosystem might not be good for monetizing but as a closely-knit focus group, it is extremely popular.