Well, right before New Years. <a href="http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat">The bulletin states that Dec 31, 2008 will have 86401 seconds</a>. There will be a December 31, 2008 23:59:60!
UTC TIME STEP
on the 1st of January 2009
A positive leap second will be introduced at the end of December 2008.
The sequence of dates of the UTC second markers will be:
2008 December 31, 23h 59m 59s
2008 December 31, 23h 59m 60s
2009 January 1, 0h 0m 0s
The difference between UTC and the International Atomic Time TAI is:
from 2006 January 1, 0h UTC, to 2009 January 1 0h UTC : UTC-TAI = - 33s
from 2009 January 1, 0h UTC, until further notice : UTC-TAI = - 34s
Leap seconds can be introduced in UTC at the end of the months of December
or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
six months, either to announce a time step in UTC or to confirm that there
will be no time step at the next possible date.