According to reserach we could not find any evidence of a separate, sustained Oz-dedicated talk-show podcast that launched in 2006 (or earlier) other than this Returning to Oz / Ozcast material here.

There has been at least:

• read-aloud / audiobook style podcasts of The Wonderful Wizard of Oz with episode dates in 2005–2006, or

• single one-off Oz episodes inside broader film/history talk shows or radio programs, or

• archival radio dramatisations made available online — but not a new Oz-only talk-show/podcast series launching in 2006 besides Aaron Pacentine’s work.
  
  We must not forget some of the early "Oz" show from the 1940s and others that did dramas but some that have been many one off episodes...but we believe we have been the first with the "Returning To Oz" radio show!