There are 1.4 million business pages on Facebook, with an average of 100 fans each

"Facebook doesn't break out figures for small businesses but says it has 1.4 million business "pages," with an average of 100 fans per page. Facebook Chief Operating Officer Sheryl Sandberg said in a speech in New York last month that every day, 10 million people become fans of pages. (Many of those pages are for random concepts, such as the beach, or laughter, or even one called "I don't sleep enough because I stay up late for no reason," which has 3.5 million fans.)"
Source: LA Times, 27th October 2009