The iTunes Connect notice, obtained by RazorianFly (via Cult of Mac), breaks down the new image size requirements, warning that non-compliance will result in an app being held for review until the proper screenshots are provided.
Apple's new app screenshot requirements:
- 640 pixels by 1136 pixels (portrait)
- 640 pixels by 1096 pixels (portrait)
- 1136 pixels by 640 pixels (landscape)
- 1136 pixels by 600 pixels (landscape)
A number of third-party developers have already submitted updates to bring their apps up to iOS 6, and subsequently iPhone 5, standards, including a handful tailored to take advantage of Apple's Passbook app.