Funny that you mention steganography and WoW. Turns out that Blizzard watermarks your screen as you play with information like your server, user info, etc.
Not adding to the discussion in any way, but I really enjoyed scanning through this, knowing the information had already been decoded, and seeing people post 'you're all morons, it's just a jpg artifact!'
http://www.tomshardware.com/news/watermark-screenshots-World...