That's nice and all, but now, aluminum stuff becomes discolored---dull, dark, and blotchy.

Is there anyway to restore it back to shiny aluminum color?

I found this information on the Seventh Generation website:

"In general, dishwashers are not a safe environment for anodized aluminum cookware. The reason for this is both the nature of automatic dishwasher detergents and the nature of the automatic dishwasher process.

Aluminum is a very reactive metal, and the surface is rendered less active by the process of anodization. However, automatic dishwasher detergents are caustic and will attack the aluminum.

But the dishwasher environment itself is hazardous to aluminum! Many consumers improperly mix different types of metals in their automatic dishwasher. They may have silver, stainless steel, and aluminum present in a single wash. Mixing different metals in water creates a battery. One metal dissolves another while generating a flow of electrons! Unfortunately, aluminum is usually the metal that gets dissolved, resulting in pitting and discoloration of the aluminum cookware."

You can also read what Consumer Reports says about discolored aluminum at the link attached.

That's pretty cool, though that different metals create a battery.