WSS/MOSS Certifications - I did it
Years ago I used to be skeptical of certifications. My argument with my manager was that you learn stuff doing things hands on and not rote. But, times have changed. MOSS/WSS is a very wide area and getting deep hands on experience in all the departments is hard to come by. In my humble opinion, this is where certifications come in handy. It is a comitted exercise which makes you take a deep look into all nook and crannies of a complicated software.
BTW, I passed the 4 exams - WSS/MOSS app dev & configuration a couple of weeks ago.