I recently happened to interview a candidate boasting of SCJP 5.0 (Sun Certified Java Programmer 5.0) and I asked her few basic questions in java regarding String and StringBuffer and she didn’t have a clue about it. She wasnt even aware of the basics in Java, but she said she had a score of 95 , and well I was shocked that shes got a better score than mine 🙂
Same thing happened with a candidate who had newly joined the company (though with 2+ years of experience) , Â and he boasted a SCJP and SCWCD , and still didnt have a clue with writing a JSP.
On the other hand I have been working with these technologies for quite  a few years and when I eventually took these certifications, I felt  confident that I can answer almost anything in any interview. But probably the interview panel who sees my certifications will treat me just like the above mentioned candidates, afterall passing these certifications (which require 70% to pass) doesnt guarantee anything.
It could be very well with the way you prepare for facing these exams, if you solemly try to learn the questions in the dumps by heart, you might end up with nothing but a paper which says you are certified, on the other hand if you thoroughly go through books and specifications it will make you a expert in the area. So its upto you to decide what you really want.
My conclusion is these certifications do help individuals taking  them in gaining valuable knowledge , but it doesnt really help employers to gauge a candidate.