Apparently the comet passed by the earth in 2007 along what was originally described as a hyperbolic path -- meaning it would make its way through the solar system and never return. Somewhere along the way its trajectory was altered and it ended up in an elliptical orbit that is typical of a periodic comet. So now it is back three years later. That's a very short period for a comet.
The 2007 visit was spectacular, but didn't get a lot of attention here in the U.S. because it was mainly visible from the Southern Hemisphere. It was clearly visible during daylight hours for a while, and some of the most spectacular images I've seen are the ones that show the long wisp of the comet's tail rising from the horizon even as the head was no longer in view above the horizon.
