Xiph QuickTime Components
The xiph quicktime components (xiphqt) is a set of quicktime plug-ins supporting xiph media compression formats. it is all you need to start using xiph-formatted media files in a variety of quicktime-based applications - for example, listening to ogg/vorbis files in itunes or producing ogg theora with imovie.
http://www.xiph.org/quicktime/