Yes, and an incredibly effective one at that. I read the book The Facebook Effect and found that this site is more powerful than most people take it to be. I think that the principle of making business promotion a SOCIAL thing holds true for all businesses just differs in the scale. It is perfect for everything any business could ever ask for--announcing business updates and making sure they are heard, building loyalty, creating awareness about your business, getting to know your market and letting them know what business you are. A simple like from one user could result in 2 and 2 could turn into 4 and so on. It's important for any serious business to use at least one tool like this.