iPhoto 5.0.1 is an update to iPhoto version 5. First released by Apple Inc. on February 2, 2005, it first sufferd from an "availability problem", where it would refuse to turn up in Software Update if the user did not remove an Installer package with "iPhoto" in its name (most affected is the package "iPhotoUpdate403.pkg") in /Library/Receipts. (Apple is expected to address this shortly.)
The update addresses issues with upgrading iPhoto 4 libraries. Also addressed are problems relating to dragging albums into folders and the importation of MPEG-4 movies. Some other minor fixes are also included.