It’s been brought to my attention that Google Earth 4.3 only shows the first image that is viewed in a the KMZ files produced by iPhotoToGoogleEarth. After that all images in that file are shown as just question marks. This is not a bug in iPhotoToGoogleEarth, it complies with the KML specification and has not changed in a while. Google Earth however has changed and other people have noticed it too. According to this bug report you can view the images if you decompress the file first (rename the output to have a “.zip” extension and double-click it), or use the PC version of Google Earth. Other than that it’s just a matter of waiting for Google to fix the bug.
UPDATE: Now that Google Earth 5 is out the issue has been resolved. Please upgrade your software to see all the photos that iPhotoToGoogleEarth produces.