Perhaps last minute bugs or issues are causing a delay in the launch of the service. (imore.com)
Of course, if any last minute bugs are found the update could be delayed making the information presented here tentative. (windowscentral.com)
Being an Indie Developer is rough, especially the one or two man dev shops which makes up the unsung majority of Indies, there is a lot of work to creating a game and when pressed to decide between making a fancy set of screenshots to pass around or fixing some last minute bugs most will choose to fix bugs. (gamemakerblog.com)