iPhoto 9.2.3 fixes a multiple user confliction issue and brings minor performance bumps.
From the change log:
Improves overall stability
Addresses an issue that could cause iPhoto to quit unexpectedly on systems with multiple user accounts.
The newest version is recommended for all users of iPhoto '11 and requires Mac OS X 10.6.8 or OS X Lion 10.7.3 or later.
The update comes in at 354.55MB and can be downloaded through Apple's or Software Update.
[ View article on AppleInsider ]