I would say meta description tags are important, not as much as they used to, but they are still important, it certainly helps in the serp’s rankings.
- First it can be used for SE as a text to be displayed in the serp’s, which can help increase the number of clicks if done correctly.
- It helps that the pages in your site don’t get penalized for duplicate content, as if you had the same description for every page on your site.
Check the following link:
http://www.seomoz.org/blogdetail.php?ID=1540