[todd8]

All the Network Time Protocol servers that I know of handle leap-seconds in one way or another. Some do leap-second smearing and I believe that newer versions of NTPD and OpenNTPD both support smearing. However, it appears (with only a cursory examination) that the Google time servers start smearing before the actual leap second is inserted and I've never seen that done anywhere else (or I missed it by reading too quickly).

See https://news.ycombinator.com/item?id=10199686

Also note that big changes in the way time is handled (leap seconds, etc.) in the near future because of the upcoming meeting of the International Telecommunication Union (ITU) at the World Radiocommunication Conference in November 2015.

[sla29970]

The ITU has 4 methods for dealing with leap seconds, and method D is to change nothing. See the lack of consensus for any change in last week's presentations at http://www.itu.int/en/ITU-R/conferences/wrc/2015/irwsp/2015/... especially the "Input Document WRC-15-IRWSP-15/8" presentation by Zuzek.