I've recently been dabbling in fixed layout our epub creation, to produce comic books. The comic books I make have extremely simple layouts, I.E, each comic page (including the cover) is a single image.
InDesign already has an export to fixed layout epub option, however it would be cool if you could export photoshop layers to a fixed layout epub.
If it was possible to export to a fixed layout epub some export options would come in handy.
Assign cover image (default to top layer)
Allow the creation of Dublin core metadata elements
Choose image compression (if any) options. Ideally, options like in the save to web legacy has
Baring that idea, exporting layers to InDesign or single PDF would be the next best option.