a@chordstudio, did you upload any of your panoramas to your account here on Photosynth's website? If so, it should be easy to view them in the app again by visiting your own profile page: http://photosynth.net/userprofilepage.aspx?user=chordstudio
If you did not upload your panoramas to the website, it may be the sad case that iTunes failed to correctly back up the saved data of your iPhone 3's Photosynth app.
If you still have your iPhone 3, you can try what a3rdparty suggests here: http://photosynth.net/discussion.aspx?cat=c76bfe71-d042-4aec-b49b-b48b67d7be96&dis=6aa35f4a-2a31-4adf-b50a-03e556466c2e
The flat versions of your panoramas that you see in your camera roll are not the same as the cube maps that the interactive viewers in Photosynth's mobile app and website use, so I'm afraid that if iTunes deleted your cube maps you'll never quite get them back from the flat versions.