Apple have just released Apple Aperture 1.5.2, which addresses some issues related to overall reliability and performance in a number of areas of the application (see list below). The download is 131Mb. This update is recommended for all Aperture users.

What’s New in this Version
• Contact sheet printing
• Smart Albums
• Watermarks
• Lift and stamp
• Image export
• Versions created using an external editor

Note: If you haven’t already done so, it is strongly recommended that you also download the Digital Camera RAW Support Update 1.0.1, which is available on the Apple Downloads support page at http://www.apple.com/support/downloads .

The Digital Camera RAW Support Update provides RAW file format compatibility for the following digital SLR cameras:
• Canon Digital Rebel XTi / 400D / Kiss X Digital
• Nikon D80
• Pentax *ist DS

The Digital Camera RAW Support Update also addresses the following issues:
• Handling of large Canon RAW files (.CRW)
• DNG compatibility on Intel-based Macintosh computers
• Lines sometimes appearing in images exported from Aperture

http://www.apple.com/downloads/macosx/apple/aperture152update.html