See clip from Attorney Rajiv S. Khanna's conference call video that addresses this question.
The employer will be in a lot of trouble. The law is employers cannot bench or reduce the salaries of the employees just because they are in between projects. They are required to pay the full salary. If they don’t you can file a complaint with the Wage and Hour Division (United States Department of Labor) within a year when the wages were not paid. The form is WH-4. Once you file the complaint, Department of Labor investigates it. You have to do nothing. It does not involve any expense at your part for H-1 holders. Department of Labor will recover the money and will get the cheques that are due. Secondly if the employer has the practice of doing this in a routine basis then the company can be in a lot of trouble. Please do not get involved in a situation where the employer runs the payroll and you return the cash to them. If that is the situation anybody invites you to that is a party to a fraud. Fraud and misrepresentation can result in criminal prosecution and also can result in a permanent bar from entering the United States.