Recently, TidBITS reader "Rene Belloq" alerted us to a large and growing thread on Apple's Support Discussion forums (currently at over 20,000 views and nearly 300 replies). The thread details various user encounters with an iPhoto '09 bug that prevents the Faces feature from recognizing additional matches for already-identified faces. Users find that, upon attempting to find other matches for a particular face, spinning progress arrows appear next to the text, "X may also be in the photos below." For most affected users, no matches are ever made, and the arrows continue to spin. In some cases, after an inordinate amount of time, iPhoto returns a random group of off-the-wall suggested matches.
The problem has affected users running both Leopard and Snow Leopard, a variety of Macs, and libraries ranging in size from less than a hundred photos to tens of thousands.
Several solutions have been suggested in the forum, including rebuilding the Faces database (sometimes with iPhoto Library Manager), repairing permissions, uninstalling and reinstalling iPhoto, and more. Unfortunately, no solution appears to work reliably, and for those who do seem to find temporary relief via one of these methods, the issue inevitably returns.
Apple service representatives told Belloq - who remains plagued by the problem - that they are aware of the issue, have opened a bug on the problem, and will be issuing an update to iPhoto '09 to resolve it (though no release date has been set).
The Apple engineers also noted that the problem appears to be related to the face recognition engine getting hung up or confused. The issue may also be triggered by additional factors such as library size and the inclusion of MPEG videos in a library.
If you are experiencing this problem, there's little you can do about it beyond waiting for an iPhoto update to be released. Should you feel the need to take some kind of action, you could consider adding your experiences to the ongoing forum thread linked earlier or contacting Apple (either online or by working with an Apple Genius at a retail store) to voice your concerns. We'll keep an eye on this issue, and hope that Apple issues a fix sooner than later.