Facebook buys GowallaBy Laurie Segall @CNNMoneyTech December 2, 2011: 8:40 PM ET NEW YORK (CNNMoney) -- Facebook has acquired location sharing service Gowalla for an undisclosed sum, according to a source close to Gowalla. Facebook declined to comment on the deal. "We don't comment on rumor and speculation," a company spokesman said. Most of Gowalla's employees, including founder Josh Williams, wi