Today is the first cross-quarter day of 2009. What that means is that we are halfway between the winter solstice and the spring equinox. In some parts of the world the cross-quarter days are used to determine when the seasons begin and end rather than the astronomical solstices and equinoxes. Even though many people have never heard of the term cross-quarter day, they have heard of the holidays associated with them.
February 2: Groundhog Day
May 1: May Day
August 1: Lammas
November 1: All Saints Day (October 31: Halloween (All Hallows' Eve))
And for those that were wondering why we have six more weeks of winter if the groundhog sees his shadow, it is because there are approximately six more weeks until the spring equinox (it's actually closer to seven, but six is close enough) when spring "officially" starts.