Maybe on Android, but iOS does not have the [public] APIs to allow for that. There used to be a notification called PictureWasTakenNotification that was fired after a picture was taken, but that disappeared in iOS 5.

Snapchat notifies of a screenshot, but the screenshot can still be taken. The theory is Snapchat checks the photo album count and if there's an additional photo it assumes a screenshot and will notify the other party.

Here's a discussion on the topic:

http://stackoverflow.com/questions/13484516/ios-detection-of...