Preview at WWDC likely in June, followed by September launch.
Taller 'iPhone 5' Cases Begin to Appear for Sale
Smaller bottom dock, and headphone jack
Cydia Blog notes the appearance of "iPhone 5" cases from TVC-Mall that correspond to circulating rumors about the next generation iPhone.
The case design lines up with the many part leaks and schematics that have been floating around for the past several months.
The appearance of case designs shouldn't be that surprising given the numerous leaks we've already seen. The cases, however, do represent some small level of confidence by Chinese manufacturers that the next generation iPhone will match the circulating rumors. This includes a slightly taller/thinner design with a smaller bottom dock connector and a bottom-placed headphone jack.
The next generation iPhone is already said to be in production for an expected fall launch.