Today Jupiter is at its closest point to Earth for 2010, a mere 368 million miles. Although not a particularly astonishing event, it is nonetheless a prime time to get out your binoculars or telescope to view the giant planet as it dominates the night sky. Jupiter is a fun target to view up close because it offers so much to see: Four bright Moons, colors and textures from its cloud belts, and for a brief time right now it guides you to find the distant planet Uranus.
Every year as the Earth moves around the Sun, at some point in time it is at its closest approach to Jupiter. This moment is called "opposition" and is when the Earth, Sun and Jupiter are all in a perfect line. Each year the distance between the Earth and Jupiter might be a bit more or less depending upon the circumstances of each planet's orbit. This year, the distance is smaller than usual (closest since 1963 and until 2022), but that difference is relatively small from year to year. More important is that the planet is at its brightest for the year, and remains high in the sky for optimum viewing for the entire night.
Sky and Telescope Magazine has an excellent article about this close encounter if you want more details.