I have been looking for this for a while but the time has come: the Xiph project released an important update to their QuickTime component that allowed to playback Ogg container files with Vorbis encoded audio.
The latest update (0.15) now includes Theora support as well effectively bringing free audio and video media codecs to the Mac throughout the system (read: all applications) including iTunes and all Web Browsers. I love the QuickTime framework for making this so easy and do appreciate the work of the Xiph team to have taken up on this task. With the Mac being the premier platform for doing media work, this is a wise move. It makes free media formats available on commercial grade systems which can lead to a wider acceptance.
The component seems to work fine for both playback and export which makes it easy to convert Theora content for the iPod or other uses. Unfortunately, the component does not yet contain the proper importer functionality so I can’t use it to create Theora content using standard QuickTime export which is sad. That way any video producing app could directly export to Theora without any additional processing.