Barry Schwartz over at Search Engine Roundtable has a great find via Google Groups. Vanessa Fox of Google's Webmaster Central is recommending the use of meta description tags. The questioner within the groups must have had some issues with how they were appearing in Google's search results, and must not have been utilizing the meta description tag.
Andy Beal from Marketing Pilgrim already commented and I'm in agreement with his thought, that although they are recommending the use of the meta description tag, it's not for ranking purposes. I wrote a about the using this tag along with the page title tag back in June of this year (Smart Search Marketing: Titles & Meta Descriptions). Barry has more over at SE Roundtable about Vanessa's recommendation.