Africa is the new India, or something like that. Investors desperate for yield might do well to shop around for good buys in the continent, says a new report from Société Générale. There are risks, for sure, but even WalMart has its eye on Africa's growing middle class. The number of families with an income of more than $20,000 a year exceeded India's at the end of 2008, according to McKinsey & Co.