As a manager I would give some weighting when recruiting new staff, but the importance of them is minimal compared to the importance of previous work experience. I would hire someone with better experience over someone with every MS cert available.
I'd prefer to give someone a programming quiz\exam during the interview process than rely on someones MS Cert on their cv.
I am MS certifed in SQL Database Dev\Admin for example and I know that all the questions\answers used in the exams are easily available on the web. You still need to study and know your stuff but I don't believe they hold a huge value.