Facebook Places, unveiled late Wednesday, is a highly-anticipated new location-based service that will allow Facebook users to "check in" to boutiques and bars, restaurants and theaters, places, then share their location, via Facebook, with their friends.
Facebook Places joins the ranks of several existing location-based social networks, such as Foursquare and Gowalla, which also allow users to share their locations by "checking in" to places and earn real-world rewards, like coupons or discounts, for their patronage of businesses.
How does Facebook Places work? How is it different from Foursquare or Gowalla? Can you control your privacy? Who sees your check-ins (and what's a check in??)?