New Horizons is due to get to Pluto in 59 days (closest approach on July 14). It has already taken photos of the small Plutonian moons. We’ve known about Pluto’s main moon Charon since 1978. The Pluto / Charon system is interesting because the barycenter of the two is outside the body of the primary. This means that the center of mass for Pluto and Charon is above the surface of Pluto.
The smaller moons were discovered in 2005 (Nix, Hydra), 2011 (Kerberos), and 2012 (Styx). They are orbiting Pluto over twice this distance of Charon. These are very small with the largest up to 172 km across.