Apple today released Aperture 1.5 Update which delivers more than 20 new and enhanced features that improve file management, metadata handling, and image adjustment. This update also addresses numerous issues related to overall reliability, performance, and compatibility.
Aperture 1.5 is a free upgrade for those who already own the application.
New features in Aperture 1.5: http://www.apple.com/aperture/newfeatures/
More info and download link (125MB) here.