If successful, the New Horizons Pluto flyby spacecraft will be the fastest vehicle to ever depart the Earth. From this Aviation Week article:

The New Horizons Pluto flyby spacecraft is poised to become the fastest vehicle ever to depart Earth, blazing outbound at 10.07 mi. per sec.--zooming past the orbit of the Moon in just 9 hr.--on the first mission to the last known planet.

New Horizons' velocity will be about 10,000 mph. faster than most previous Earth escape flights to the Moon and planets.

Flying at 36,000 mph.--the Earthly equivalent to about Mach 50--New Horizons will reach Jupiter in only 13 months. Relative to the Sun, its Earth escape velocity will be 28.8 mi. per sec.

Launch of this "fantastic voyage" on 2.4 million lb. thrust from the most powerful version of the Lockheed Martin Atlas V is scheduled for 1:24 p.m. EST Jan. 17. There will be daily launch windows to Pluto through Feb. 14 should weather or technical factors scrub the first opportunity.

The article goes on to say that the booster will be pulling 2 Gs right off the pad. However, if the launch is delayed past January 28th, there will be serious consequences for the mission timeline.

Pluto is the last unexplored known planet in the Solar System--six times more distant than Jupiter and three times farther than Saturn. Voyager 2 took 12 years, from 1977-89, to fly by Jupiter, Saturn, Uranus and Neptune.

By comparison, New Horizons will take at least 9.6 years, on a more direct, higher-velocity trajectory, just to reach Pluto. And the trip will be 1-4 years longer if the mission slips into the Jan. 29-Feb. 14 part of the window.

Those latter launch trajectories would involve a "direct ascent" to Pluto, minus the gravity assist to 47,000 mph. by Jupiter on the best trajectory. A similar backup direct ascent window with arrival in 2019 is available in February 2007.

Stardust reentry on Sunday and the Pluto mission set to go on Monday. Let's hope everything works as advertised. Looks like a good weekend for space activity.