A company hiring H1-B workers must show that they're paying average+ wages for the position [1]. They need not disclose actual salaries paid to individuals, nor are they precluded from paying above market rate.

1. http://en.wikipedia.org/wiki/H1b

Employers must attest that wages offered are at least equal to the actual wage paid by the employer to other workers with similar experience and qualifications for the job in question, or alternatively, pay the prevailing wage for the occupation in the area of intended employment, whichever is greater.