So last week we ran across this report about how the market for mobile transactions is about to explode, increasing from about 68 billion dollars in 2009 to about 633 billion by 2014. Entrepreneurs are salivating about this possibility and we recently saw the launch of Square. Then there are online services like Venmo and Zong, which were not named by grabbing Scrabble tiles out of a bag, contrary to appearances.

But the idea of a bustling mobile phone based economy is nothing new if you’ve paid attention to how day to day transactions are handled in Africa. In several developing nations there, people who don’t have access to checks or credit cards have evolved a robust and versatile economy built around simple cell phones.

Ethan Zuckerman is a senior researcher at Harvard University’s Berkman Center for Internet and Society and he’s lived and traveled extensively throughout Africa. He’s closely followed technology in that continent. We talk to Ethan about what the cell phone economy means.