Does Google use the Meta Description tag? Check out these comments. Some same Meta Description tags are ignored by Google. This Google Groups post by Google's Vanessa Fox has this comment saying you should use the meta description tag:
Looking at your site in the search results, it appears that your pages would be well served by meta description tags. For most queries, the generated snippet is based on where the query terms are found on the page, and in those cases, your results are fine. But for some more generic queries, where a logical snippet isn't found in the text, the generated snippet seems to be coming from the first bits of text from the page -- in this case, boilerplate navigation that is the same for every page. Source
And this comment cements the need for unique Meta Description tags when optimizing for Google:
...by adding a meta description tag, a unique one, for each page, Google will use that information as extra criteria to determine the uniqueness of the page...Otherwise, Google will use the top text of your page's content, and that can potentially be your top navigation or worse. Source