hi Scott,
it's somewhat working for me on Windows, but only when using the audio.clip.GetData / SetData. right now i am trying to use the OnAudioFilterRead() but it's glitchy (i can hear pd running but it's mostly noise).
you can see an attempt here: http://goo.gl/BWdo4
here's my github: https://github.com/patricksebastien/libpd4unity
OnAudioFilterRead(): http://goo.gl/WE2Xx
keep us updated!