

Apple has released a version update for iPhoto that should prevent the possibility of data loss when upgrading to iPhoto '11.
A support document walks through the process to prevent this from happening. The instructions, however, are a bit confusing. It seems you must upgrade to iPhoto 9.0.1 after you've installed iLife '11 but before you launch iPhoto for the first time. The launching if iPhoto initiates the upgrade process to your iPhoto library which is where data loss can occur.This update addresses issues that, in extremely rare cases, could result in data loss when upgrading a library from an earlier version of iPhoto.
Before an existing iPhoto library can be used with iPhoto '11 it must be upgraded. This process occurs when you open your library with iPhoto '11 for the first time. In extremely rare cases, if you do not follow the recommendations below during the upgrade process you may experience data loss. This article outlines the various events that may occur during the library upgrade process and offers advice on how to avoid data loss.
Article Link: Apple Releases iPhoto 9.0.1 to Address Data Loss