iPhoto comments and ratings are stored in the proprietary iPhoto database file. If your databases is corrupted or you change to a different photo management program, you will lose your iPhoto ratings and comments.
I am writing an iPhoto plugin that will write this iPhoto info to the EXIF and IPTC fields in the actual jpeg (photograph file). That way, you can keep the comments and ratings if you change to another program or if your iPhoto database is corrupt.
I will actually sync the data between the jpg file and iPhoto. So if you use another program like iView Media Pro or Adobe Photoshop to write EXIF or IPTC metadata, that info will appear in your iPhoto ratings and comments (if you want it to).
If you are interested in this iPhoto extension, please email me at iphotoexifsync@andyozment.com and let me know. Also, let me know what you think the appropriate price for a plugin like this would be.
I am programming this extension as a microISV (uISV) project: I want to see if I can write programs as a part-time job. So I will have a blog in which I discuss the iPhoto extension and my progress as a business. I’m still setting up the web page, as you can see: I’ll write more as I progress!