[UPDATE: Starting March 1, 2011, certain retail employee will be entitled to breaks.]
True. According to the Maryland Department of Labor: "There is no law requiring an employer to provide breaks, including lunch breaks, unless the employee is under the age of 18."
But if an employer gives you a "break" you must be completely relieved of your duties for at least twenty minutes. Otherwise you are working and should be compensated for this "break" time. See this post.