Sorry if I'm not clear - I'm rushed for time right now else I'd setup an example in povray to illustrate.
Yes, I'm talking about correctly rendering alpha maps, which PNG would support, but also rendering _shadows_ of alpha-mapped-textured objects correctly. In my "tree" illustration, the object is just a rectangle, so if its treated as a solid as anim8or does now, you'd see a rectangular shadow cast by it.
If the rectangle, however, is textured with a PNG that uses transparency, it'd be great if the shadow also used the alpha map of the texture. For instance, if the rectangle is textured to a tree, you'd ideally see the tree being rendered and other objects behind it (eg support for the alpha maps) and you'd also see the tree cast a tree-shadow, not the rectangular shadow of the object its mapped onto. Hope that makes it clearer.