  We address several issues regarding the interpretation of galactic \ggg-ray
sources. We consider powerful pulsars in binaries producing X-ray and gamma-ray
{\it unpulsed} emission from the shock interaction of relativistic pulsar winds
with circumbinary material. Nebular mass outflows from companion stars of
binary pulsars can provide the right {\it calorimeters} to transform a fraction
of the electromagnetic and kinetic energy of pulsar winds into high energy
radiation. We discuss the physics of interaction of relativistic pulsar winds
with gaseous material and show that the conditions in pulsar binary systems
might be ideal to constrain shock acceleration mechanisms and pulsar wind
composition and structure. We briefly discuss the example of the 47~ms pulsar
PSR~1259-63 orbiting around a massive Be~star companion and monitored by X-ray
and gamma-ray instruments during its recent periastron passage. In addition to
young pulsars in massive binaries, also a class of recycled millisecond pulsars
in low-mass binaries can be interesting high energy emitters.
