I just stumbled on this tool, that tells you now, if any of your photos do not meet the new requirements for photo size effective July 1. With just over 5,000 items this was a great tool for me to check all of my photos.
http://www.isdntek.com/demo/test/SellerEpsPhoto.htm
Great product, makes it easy to see which photos you need to redo. Now if they would only create a watermark test tool........that would be grand!