In my company there are a mix of people with and without various certifications. 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.