while others will jump in with info that will answer you question, I have a recipe that
I have used several times that uses *only* baking powder.
You can see the recipe and the topic of discussion here : http://www.pizzamaking.com/forum/index.php/topic,2615.0.html
As for the combo of yeast *and* baking powder .... - I have never heard of it.
I do however use a pancake recipe that uses both baking powder *and* baking soda
and there's a reason both are used, but I don't recall what that is now
Anywhooo, I'll stop there, as this isn't on-topic for your question.
Let's see what others come up with, it's a very interesting question you posted.