Are You Ready to Set Your Clocks Back...

...One second?  Leap Second Will Cause 61-Second Minute Midnight Saturday

The transition from June to July will be delayed by circumstances beyond everyone's control. Time will stand still for one second on Saturday evening (June 30) because a "leap second" will be added to let a lagging Earth catch up to super-accurate clocks.

I wonder what effect this has on systems like GPS that rely on ultra-accurate timing.  Do they keep time using some "universal" time... Oh yeah, I have the internet; I don't need to know anything, I just need to find the answer:

While most clocks are synchronized to Coordinated Universal Time (UTC), the atomic clocks on the satellites are set to GPS time (GPST; see the page of United States Naval Observatory). The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections that are periodically added to UTC. GPS time was set to match Coordinated Universal Time (UTC) in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset with International Atomic Time (TAI) (TAI – GPS = 19 seconds). Periodic corrections are performed on the on-board clocks to keep them synchronized with ground clocks.

The GPS navigation message includes the difference between GPS time and UTC. As of 2011, GPS time is 15 seconds ahead of UTC because of the leap second added to UTC December 31, 2008. Receivers subtract this offset from GPS time to calculate UTC and specific timezone values. New GPS units may not show the correct UTC time until after receiving the UTC offset message. The GPS-UTC offset field can accommodate 255 leap seconds (eight bits) that, given the current period of the Earth's rotation (with one leap second introduced approximately every 18 months), should be sufficient to last until approximately the year 2300.