Consumers spent about $5.5 billion at local retail stores on Small Business Saturday last year, according to a Redshift Research study commissioned by event organizer American Express.  That accounts for a little under 10 percent of the estimated $59.1 billion shoppers spent over the course of the weekend, according to estimates from the National Retail Federation.  There was a 67 percent consumer awareness level of the event in 2012, according the Redshift study.  Last year also saw 46% of independent merchants plan to participate (see "Nearly Half of Retailers to Participate").
American Express began its "Small Business Saturday" campaign in 2010, to encourage consumers to "shop small" the day after Black Friday by patronizing small, neighborhood brick-and-mortar merchants, hoping they would spend a larger share of the busiest shopping weekend of the year with these locally-owned stores.
Both American Express and its Premier Partners (Twitter, FedEx Office, USPS, and Foursquare) are offering marketing support, including a $100 ad credit from Twitter, two free professional quality 11"x17" posters from FedEx Office, $50 in ad credits from Foursquare, and a "Shop Small" doormat and 20 reusable shopping bags from American Express. 
More advice and tips and advice on how to capitalize on Small Business Saturday can be found on the U.S. Small Business Administration website.