The New Horizons probe destined for Pluto is hurtling towards Jupiter now for an additional speed boost. On the way, the science instruments will be getting a bit of testing making observations of Jupiter and its moons. Should be a good workout for the system.
After the probe's encounter with Jupiter, it will be speeding off towards Pluto at a pretty good clip of 52 000 mph (nearly 84 000 km/h or 23 km/s). That will make it the fastest probe sent out to date. Even at that speed it won't reach Pluto for another 8 years though. You can follow the probe's trajectory here.
Neat stuff. It will be cool to see what kind of things we'll learn about Pluto in 8 years time.