Today, December 21st, at 7:22 p.m. Eastern Standard Time, the Winter Solstice arrives. What does this mean, exactly?
It is the longest night of the year, and therefore the shortest day.
If you were to trace the path of the Sun across the sky today, and note how high off the horizon the Sun was when it was due south, at the apex of its arc, then that point on the sky is the lowest it will be all year. In other words, tomorrow, the apex of that arc will be a tiny bit higher, and the next day it'll be even higher, and so on. On June 21, 2007, the arc will be as high as it can be, and then it will inexorably start to drop again.
If you are in the southern hemisphere, then switch everything I'm saying here. Down is up, summer is winter, war is peace, and we have always been at war with Oceana (and I hear the chocolate rations are being increased).
The seasons are not caused by our distance from the Sun! In fact, we reach perigee perihelion (closest approach to the Sun) on January 3, 2007. If you are in the southern hemisphere, this may cause more confusion. That's your own fault for living upside-down.
You still can balance an egg.
If you want more info on the solstice, try Sky and Telescope's page, or the U.S. Naval Observatory's FAQ page. And thanks to the Morehead Planetarium for letting me steal that image, even if they maybe don't know I did so much.