Apple has patched a few stability and performance issues in Aperture with a new update for the program, bringing the version to 3.1.1. The update specifically fixes problems with the iLife Media Browser, and also addresses problems with publishing to online services such as MobileMe, Facebook, and Flickr.
The majority of the fixes address unexpected quits or system hangs that happen when performing specific functions such as fitting slideshows to soundtracks and importing photos from cameras, but the update addresses some rare problems where photos could be deleted or improperly imported during the import process.
For people who have not yet upgraded to Aperture 3.1, the update addresses problems people have had with updating existing Aperture libraries, which may benefit some who have not yet upgraded but are planning to do so. Despite this, however, be sure to back up any library you have not yet opened and updated with Aperture 3.1 before applying this update.
The update requires OS X 10.5.8, or OS X 10.6.2 or later. It is available from the Aperture 3.1.1 download page (357.79MB) but also should be available via Software Update for those who have Aperture 3.1 installed.