Remember when microwaves were first introduced and we spent hours blowing up marshmallows? Well, the news that microwaving sponges for two minutes kills bacteria created a similar such phenomenon. One important tidbit of info, though:
the sponge must be wet when you put it in the microwave!
Many news outlets received complaints when folks experimented at home with their microwaves and sponges. When nuked, the dry sponges were fried and created quite a stink. Another note: stick to nuking wet sponges only, and put plastic dish scrubbers in the dishwasher.