We don't use them for filtering candidates for jobs because the 'false positive' rate is simply too high. Instead, we use certification exams as a way of getting ready for a new (to us) technology or to bring a developer up to speed before changing projects.
So overall, I'd say certifications carry slightly more weight than simply listing what technologies you are experienced with, but much less than being able to talk about practical experience.
I agree. I sometimes interview people that we consider hiring, and the certifications doesn't play a big role for me. It's rather simple to get them.
But as other people mention, I sometime take one myself if it is a new technology or something that i'm not so familar with.
I don't know if this also is a culture thing? My preconceived opinion is that it has a higher status in the US than in my contry, Sweden. But I don't know if this is true.