At this point in time, Blackboard rubrics cannot be viewed by students, however that will change in future versions. Until that new version comes out, you can create a screenshot of the rubric and add it to your course content.
Also in future versions, rubrics will become more integrated with grading; allowing you to grade directly from a rubric. For now, it's only a pop-up that you can view while you're grading. This tool may not offer the full functionality you need yet, but depending on your situation, you may find it useful now.
You can find more information about what rubrics are and how to use rubrics in your courses at http://www.squidoo.com/TeachCollege2.