Catalyst - 7:15 pm on Mar 30, 2012 (gmt 0)
One exception to the rule possibly LOCAL...
I've done SEO for over 11 years and although I've never done a bonafide test I have experienced several times that sometimes pages without description SEEM to rank higher.
But one exception - now I specialize in local and Google Places optimization and feel strongly that Google really likes description tags with EXACT match KW in them.
Do some competitive local searches like city dentist or city chiropractor or city plumber and you'll see over and over that the top couple sites tend to have exact match of search query in title AND description.