http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNStat.html

Pioneer 10 distance from Sun: 77.64 AU
Speed relative to the Sun: 12.24 km/sec (27,380 mph)
Distance from Earth: 11.73 billion kilometers (7.29 billion miles)
Round-trip Light Time: 21 hours 44 minutes

The next two-way track will happen on April 27-28. We were able to schedule tracks on the busy DSN schedule to allow uplink and downlink support (competition for time includes Galileo, Cassini and Ulysses). We have had to wait until April for the two-way round-trip light time (RTLT) passes, which allow the DSN to send up a strong stable signal to try to lock up with a coherent downlink signal. Pioneer 10 has 3 two-way RTLT passes scheduled in April and May. This should give us adequate coverage to contact the spacecraft or determine the reason why if it has indeed been lost.

Larry Lasher, Pioneer Project Manager