NOt yet. Use png files for odd shapes sand use shadows in the png file.
Aaah, so it's part of the plan to make it posible in the future? To make dropshadows in PNG is ok, but when you want to use the dropshadow option on a transparent PNG it will put a dropshadow on the outer boarders of the imagesquare, that's kind of annoying. I want to animate a rotation of a polygone shape, but I'll skip the dropshadow for now then.
Yes - for png it is the bounding box that gets the shadow.
I am not sure about shapes but I think they are looking into it. Hopefully they will because I am working on maps where I am using the html area tag with "poly" for shapes because rectangles are too messy for hit areas.
Use a photo editor - Photoshop. To add your shadows, then import.
It is a hack, I know. You would think that the ability to import scalable vector graphics(svg) would allow for edge detection through alpha, one day!