In fact that's not the case. Employers generally take the view that workers have a duty of fidelity to their employer, and they do not appreciate workers going public with evidence of wrongdoing. Keep the dirty linen in-house, is the view, and in fact even in-house, there may be antipathy to going above the appropriate line of supervision. Even in unionized workplaces, there are not, at this point, proper procedures and protections for whistle-blowing.
On May 31st, 2006. See this statement in context.