For paralegals: is getting a paralegal certificate worthwhile?

It seems like (formerly hiring) law firms are seeking candidates with an ABA-approved paralegal certificate (sometimes in addition to a B.A.). Can any current paralegals, attorneys or legal hiring personnel attest to the importance of this for those seeking to continue a career as a paralegal (as opposed to entering the field)? What other certifications or courses would you recommend? Finally, anyone have thoughts about the future market for paralegals?