A new big screen iPhone device (iPhone5) is now in the market, To support this 1/2" bigger screen apple recommends (Following is the Email I received):
"If you are updating your app for iPhone 5 and iPod touch (5th generation), you must provide additional screenshots to support the new screen dimensions for the App Store."
The new screenshot dimensions are:
640 x 1136 (portrait)
640 x 1096 (portrait)
1136 x 640 (landscape)
1136 x 600 (landscape)
To support default splash on retina and non-retina display older iPhone devices, we used to have default.png (320px X 480 px) and firstname.lastname@example.org (640px X 960px), To support iPhone 5, now we need to add an image of size 640px x 1136px in your resources folder.
Size : 640px x 1136px
Hope this helps!
note: Make sure It meets apple guidelines as well. Its just a information and update to help you guys with my personal notes/knowledge I gain by learning.