The retail world is abuzz with talk of cheap lightbulbs. That's right, lightbulbs. Wal-Mart (WMT 1.19%) has announced that relatively affordable LED lightbulbs will be available for sale for the first time exclusively at Wal-Mart stores and Walmart.com. Should investors care about something as trivial as a lightbulb? Absolutely. In this video, Fool.com contributor Aimee Duffy explains why.