I got this problem: \"warning: iPad: Icon-72.png: icon dimensions (0 x 0) don\'t meet the size requirements. The icon file must be 72x72 pixels, in .png format (-19014)\" w
While the solution of turning off Compress PNG images does work, it is not a good solution as it then no longer compresses PNG images. While not the most useful feature ever, it is standard and does obfuscate your images in your ipa which is usually a good thing.
This issue started with 10.7.3, today. No real solution has yet been put forward (other than to build your submissions with 10.7.2 instead.)