The National Toy Hall of Fame states that it "recognizes toys that have engaged and delighted multiple generations, inspiring them to learn, create, and discover through play. Criteria for induction include: Icon-status (the toy is widely recognized, respected, and remembered); Longevity (the toy is more than a passing fad and has enjoyed popularity over multiple generations); Discovery (the toy fosters learning, creativity, or discovery through play); and Innovation (the toy profoundly changed play or toy design)."
Given those criteria, no one could question the Game Boy's eligibility, but how long before we see the Nintendo Wii and the DS joining it?