The latest build of iOS 7 disables screenshot interruptions. The implications of this could be massive, especially with the recent growth of private messaging apps such as Snapchat. This change to iOS allows users to take screenshots of Snapchat snaps and the app doesn't notify the sender that the receiver took a screenshot. While their are other ways of getting this same effect, it just makes it that much easier.
The release notes do state that screenshots no longer interrupt touches: "Active touches are no longer canceled when the user takes a screenshot." Since this is an early iOS 7 build, it's very possible that this feature may be reset to the way it operated previously, or a new method of preventing screenshots may be introduced by Apple.
If you're currently snapping with someone on iOS 7, be aware of this issue as you won't be notified of screenshots. We'll wait to hear from Snapchat on whether or not they are working on a new method of detecting screenshots.