After cruising along just fine pushing apps to the iTunes App Store we suddenly ran into this today:
iPhone/iPod Touch: Icon.png: icon dimensions (0 x 0) don't meet the size requirements. The icon file must be 57x57 pixels, in .png format (-19014)
This comes up while trying to validate your application using the Xcode Organizer or when trying to submit (which is really just failing at the same validation step). It turns out this appears to be caused by the 10.7.3 Lion Security updates which broke the Application Loader. You can read all about it here: https://devforums.apple.com/thread/140067.
The TL;DR version is you need to grab the updated Application Loader. Quit Xcode, install the updated Application Loader, restart Xcode, revalidate, and voila! Fame and fortune await…