Shortest TC article ever. Here's the source: http://www.macrumors.com/2013/01/09...

upinsmoke · on Jan 10, 2013

Actual source: https://developer.apple.com/news/index.php?id=1092013a

Someone · on Jan 10, 2013

That is not the source of the 'To Ward of Scammers' part. Apple only tells you what will change.

http://www.macrumors.com/2013/01/09/apple-now-locking-screen... gives an explanation for the 'why':

  "This small but important update shuts down a widely used scam tactic, where
   developers would upload game screenshots to get an app approved by Apple and
   then switch them out with screenshots from another popular app.

   The scam tricked people into buying fake apps with screenshots ripped from
   another, more popular game, or a game that has not been ported to iOS at all."