Basically, the 8.8 magnitude quake in Chile changed the dimensions of the earth's tectonic plates, which in turn changed the "mass balance" of the earth.
You know more about "mass balance" than you think! Have you ever seen a figure skater pull their arms close to their body while spinning? He/she will spin faster! The same is true for the earth! A shift in mass will alter the earth's rotation speed.
NASA scientists say the length of a day is shortened by 1.26 microseconds (millionths of a second) because the earth is rotating slightly faster. Obviously, this is not going to change your life in any way. But it's interesting to think an earthquake thousands of miles away can have an impact on the entire planet. We are all connected. Maybe Avatar was onto something. NOTE TO SELF: Stop making Avatar references ASAP.
Here's the original article: NASA: Quake Shifted Earth's Axis, Shortened Day