Trying to render in Maya7, don't usually use .psd. Had my libraries in .tiff, converted, put as a .psd file node in Maya, I can't see the alpha transparency. It's strange, same file saved as .tiff with alpha channels included in Photoshop works fine in Maya, can see the transparency just fine. Same file saved as .psd(with alpha channels) gives me a white background instead of a transparent one in the viewport.
I only wanted to use .psd instead of .tiff for the sake of some mental ray shots.