Twitter (News - Alert) has announced an advertising opportunity exclusive to American Express merchants and cardholders. The partnership between the two companies was announced last month, and the ad op is getting started with a promotional offer for the first 10,000 cardholders that try it out. The promo offer provides $100 in free Twitter advertising to the card members that sign up during this initial launch.

The Twitter Advertising Blog points out that this advertising program will start off small and grow over time. Twitter users may notice a slight increase in the number of ads in the form of promoted accounts and tweets in the coming weeks.

Twitter states the new American Express partnership program will allow small businesses to connect with potential customers by promoting individual tweets or by using Twitter’s Promote Accounts ad program. The company says Promoted Account advertisers will pay a fee each time a person follows the account. The Promoted Tweets ad program streamlines much of the advertising process by automatically promoting a company’s most engaging tweets to help gain followers and spread brand messaging more efficiently.

The now six-year-old company has made several changes recently in an effort to control its growing expense sheet. According to Gawker, Twitter had a net loss of $67.8 million in 2010. However, with the recent acquisition of blogging software Posterous (News - Alert) and rolling out these new advertising opps, Twitter is well on its way to posting net gains in the not-so-distant future. In fact, eMarketer (News - Alert) estimates the micro-blogging giant, which processed about 250 million tweets per day in 2011, will generate $540 million in revenue by 2014.

The American Express (News - Alert) advertising partnership program launched Monday, March 26. Twitter set up a webpage where American Express merchants and cardholders can register for the advertising program and receive their free $100 advertising credit (first 10,000 only).