I read Rachel by the bay[1] on my RSS feed and she had a link to http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat on the 20th warning about the leap second. That looks like a good place to start. [1] http://rachelbythebay.com/w/ is a good read if you have spare time the article in question was http://rachelbythebay.com/w/2012/06/20/zune/