So, you basically want two things. Something like mp3.com for vorbis. I suspect that, should the format become popular - and I think it will, mp3.com and so on will branch out and have seperate sections for other audio formats. I don't think that this will be a problem, really. Once the format is established, this will happen.
Secondly, you want mac tools. THIS is easy. The vorbis source is really well written.
I 'ported' the code to win32. It took about half an hour, most of which was struggling with MSVC. The code is VERY portable. Once it was compiling, decoding worked perfectly. Encoding was somewhat more difficult, due to a small obscure bug - but that now works perfectly too. Porting to a mac should be comparable - I doubt it'd take more than a day for someone with any knowledge about mac programming.
Mac tools are waiting only for a developer with a few hours of time on his/her hands. If you know one - get him/her to contact the vorbis-dev list. We DO want vorbis encoders and players on every platform we can.