[buzzybee]

I do microwave the sponge after use, for about 2 minutes so that it's bone dry. The reasoning is simple: most of the bacteria are going to hang out in the water. It's still going to be infected, but it doesn't have to be disinfected. It just has to remain close enough to the ambient load of the kitchen that it doesn't obviously inflame my hands when I pick it up. After all, my hands are germy too, most of the time. The soap, water, and pressure applied during cleaning are supposed to do most of the work.