Update: USDA releases report.
“Heavy snow in parts of the Midwest could cause as much as 100 million bushels of the 2009 corn crop to be lost. According to analysts in several Corn Belt states, a significant number of acres were yet to be harvested when snow came in December. Now, with the storm that struck the first week of January adding more snow, a lot of the corn still in the field will be there for the rest of the winter. It likely won’t be harvested until spring and significant yield loss will occur.” (source)
The USDA releases its annual crop production summary estimates for 2009 January 12, 2010.
See also: 2010 Food Crisis
UPDATE: This article from The Guardian says “Food prices to soar” as the effects of the Big Freeze become evident.