If you’re a small business owner looking to make your company more social, the new partnership between American Express and Facebook might be your big break.

Starting today and until May 20th, small business owners in the United States can enter Facebook Big Break for Small Business to win a $20,000 cash prize, free one-on-one consulting about their current use of Facebook and a two-day advertising and marketing boot camp at Facebook’s headquarters in Palo Alto, CA. The training will include best practices for using Facebook, pages, ads and social plugins.

To enter the contest, small business owners need to visit Amex’s page on Facebook and provide answer to a questionnaire about their company. Amex will pre-select ten finalists and then Facebook fans will vote for five winners.

This isn’t Amex’s first partnership with Facebook to support small business owners. Last November, the two companies teamed up for the first-ever “Small Business Saturday,” which offered free Facebook advertising to 10,000 business owners who signed up to participate in the initiative. The idea was to encourage shoppers to support small business owners during the holiday season. Since then, Amex has found that over half of small businesses use social networking sites to communicate with customers and market their products.

What do you think of Amex’s Big Break promotion? And how can a smart Facebook presence transform your small business?