The Magic Eraser is absolutely amazing on hard surface because it is a micro abrasive, maybe even nano abrasive. It probably doesn't make sense on fabrics because it will probably be ripping one tiny filament at a time. I don't know, I'm just putting my two sense in.
Here's a nickle's worth. Who wants to bet that in 5 years they pull Magic Erasers off the market amoungst a flurry of law suits . . . cancer, alzheimers (sp?), lumbago, colorblindness and the choking death of a Jack Russel Terrier named Max?