Earlier this week iOS users noticed that a number of their apps were suddenly broken and unplayable. Over 70 apps including popular titles like Angry Birds were broken after a new update from Apple was deployed. It turns out the real culprit was Apple's DRM scheme, FairPlay. The short story is that, after the update was deployed, the DRM failed to recognize the game or app in question as "valid" and even uninstalling and reinstalling the app wouldn’t fix the problem. While developers and Apple are claiming that the problem has been resolved, users who installed the update during the July 3 - 5 period are still claiming to have problems.
Apple also claims that the problem was not widespread, but having 70 apps become inexplicably broken should probably not be considered "isolated incidents."
For more information on FairPlay, check out this Wikipedia entry.