From the iLife '08 Software License Agreement (found here:
http://www.apple.com/legal/sla/)
". You may use the Apple and third party audio content (“Audio Content”), contained in or otherwise included with the Apple
Software, on a royalty-free basis, to create your own original soundtracks for your video and audio projects. You may
broadcast and/or distribute your own soundtracks that were created using the Audio Content, however, individual samples,
sound sets, or audio content may not be commercially or otherwise distributed on a standalone basis, nor may they be repackaged in whole or in part as audio samples, sound files, sound effects or music beds. "