Jeff Atwood asks Do Certifications Matter? Personally I think there are two main uses for certifications:
In the first case, even though they don't mean a whole lot, I do feel better hiring someone fresh out of college if they are also an MCSD. While that doesn't mean they will come in at a higher level, it does mean that they have a better idea of the software development landscape and probably know more of what they don't know.
For the second case I think certifications matter even less between programmers, but probably have some impact in selling developers to a client. If I'm interviewing an experienced developer I'm definately much less interested in their certifications.
I personally like certifications. Not so much for selling myself to clients or potential employers, but as decorations. I enjoy taking tests and I don't spend anytime studying for the exams (unless I don't pass, then I generally see it as a real challenge). I also find them helpful because they help me to know what I know or don't know. If you take the beta exams, they are free, plus many times you get a voucher for passing them.
So to complete my analogy, certifications are like decorations and experience is like floorspace. If you have very little floorspace and lots of decorations, it will look cluttered and strange. The more floorspace you have, the more decorations you can have.
Do certification matter? I think so, but not as much as experience.