In my opinion, there is nothing wrong in receiving certificates for attending a course or for being certified or accredited to practice specific KM techniques. (Cognitive Edge, for example accredits practitioners who have attended their workshops.)
What we need to avoid is the nonsensical practice of certifying KM and awarding pretentious titles to participants such as "Certified Knowledge Manager." The field of KM is too broad, too deep and too rich for this to have any real meaning. It is often used as a marketing technique. Such courses are not necessarily bad and can be excellent but should be treated with caution.
If you are looking for a course, pick the best one for you in terms of content and learning - not just because it claims to be certified in some way. I have a section of this site dedicated to KM Education.
But think it through for yourself - here is a reading list:
KM Certification Reading List