  Gamma-rays can be produced by the interaction of a relativistic jet and the
matter of the stellar wind in the subclass of massive X-ray binaries known as
"microquasars". The relativistic jet is ejected from the surroundings of the
compact object and interacts with cold protons from the stellar wind, producing
pions that then quickly decay into gamma-rays. Since the resulting gamma-ray
emissivity depends on the target density, the detection of rapid variability in
microquasars with GLAST and the new generation of Cherenkov imaging arrays
could be used to probe the clumped structure of the stellar wind. In
particular, we show here that the relative fluctuation in gamma rays may scale
with the square root of the ratio of porosity length to binary separation,
\sqrt{h/a}, implying for example a ca. 10 % variation in gamma ray emission for
a quite moderate porosity, h/a ~ 0.01.
