I've used the ie6 transparent png support before to use the super-nice gnome png file type icons in file-storage.
the method is a pita, but i just made a memoized proc that returned an image html chunk for (in that case) a mime-type and a browser string. all the hairy stuff stayed in the proc.
you can thus present a transparent png properly for ie6, mozilla (v?) and from memory safari on macos?.
the results are v.sexy
