So is 2012-12-21 the shortest day of the year? The actual solstice occurs at different times in different years so I expect this varies. For this year, looking at the web site timeanddate.com (two d's), which I found via Google… (Sigh, the power just went out again!)
…It looks like it's actually 21 Dec, at least in Atlanta, GA. This snippet of their chart shows sun rise and set times, and the length of the day.