Meta description tags aren’t used by Google as a ranking factor, so tweaking them won’t make you rank any higher. However, the meta description tag is often used by Google to show the abstract that appears in the search results. As a result, a well written meta description tag is more likely to entice people to click on your listing rather than your competitors listing.
http://forums.digitalpoint.com/showthread.php?t=1616763
SEO Monopoly is an incredibly powerful form of SEO