ApertureToSmugMug is a plug-in for Apple Aperture to export photos to SmugMug. Download the latest version, unzip and place it into your /Library/Application Support/Aperture/Plug-Ins/Export for all users or ~/Library/Application Support/Aperture/Plug-Ins/Export folder for just your user account. You will probably have to create the folder.

If you have any questions, please ask in this dgrin.com thread.