You may have already seen the FVorbis implementation of Vorbis in Flash 10: http://people.xiph.org/~arek/pg/hx/test.html
This is a more integrated demo of the same approach: http://www.omtk.org/js/demo-mod.html
The FVorbis implementation uses lower CPU on my system, but in any case, this definitely seems like a viable approach to bring at least Vorbis to many more people - especially when combined with native support in Firefox 3.1 and the existing Java player.