Toggable glow item frames

Wouldn't it be fun if you could point out an item-framed item by toggling it on/off? Powering the block where the glow item frame hangs on to with redstone, would turn the glow item frame into a normal item frame. If the block gets unpowered, the item frame will turn back into a glow item frame.
This would be nice for servers, so you can out items hanging on item frames.