Yes, bipolar disorder and other mental disabilities are explicitly covered under the Americans with Disabilities ACT (ADA). This legislation, which was signed into law in 1990, has multiple parts that have as their overarching goal the integration of people with disabilities into all aspects of the American mainstream.
In the workplace the ADA provides some degree of protection for people with disabilities. The ADA prohibits discrimination in the workplace, including the hiring process, based on a disability.
If an individual can prove that he has a disability that is covered under the ADA, employers may be required to make reasonable accommodations in the workplace. These could include flex work schedules, a job coach, and possibly a change in position altogether.