I've read the various posts on problems displaying PNG with alpha channel. Apparently some people have had luck using GIMP instead of Photoshop. Not here. Our interactive menu design was planned to use transparent PNG, over a JPG background. I have tried saving the PNGs out of GIMP, tried displaying over PNG back, tried 8-bit and 24-bit, all result in the same display: black instead of transparent.
This is real limitation, and since Photoshop is the dominant app, it's hard to see why this fairly standard use can't be made to work.