Earthquake information is given in UCT, coordinated universal time, which is, more or less, the same as Greenwich Mean Time. (The letters are backwards thanks to the French, which is why the abbreviation for the metric International System of units is also backwards, SI). You can read about time systems at the excellent web pages of the United States' official timekeeper, the U.S. Naval Observatory.
The graph above shows how many milliseconds the length of day varies from 86,400 seconds, or 24.00 hours. The length of day is now about 2 milliseconds less than it was since I graduated from college in 1972 - no wonder I always seem behind the times. What about those shorter variations in the LOD (length of day): fodder for another blog.
The Earth, like me, is slowing down, due to the braking action of the tides, by about 1.4 milliseconds per day per century on the average. This is equivalent to 1 second every 714 days. Periodically, a leap second is added to account for this. The last leap second was added at the end of 2005.
So, if 2008 was a good year for you, you're lucky, because an extra leap second will be inserted once more on December 31, 2008.