As you can see in the video above, some folks at CeBIT in Germany this week found what is supposedly a new third party case for the Samsung Galaxy S IV. In the video they compare it to an SGS3 case and an actual SGS3 phone. The contrast is obvious as the SGS4 case has a more squared design.
One particularly interesting thing is the case doesn't appear to be much bigger than the SGS3. If this case is legit and not a scam, it would lead one to believe the SGS4 will be relatively the same total size of the SGS3, despite the larger screen size. This would suggest it will have a more "edge-to-edge" screen, and a smaller bezel. That would be a very enticing new development!
Source: GalaxyS4Forums.net via MobileGeeks - Germany