  In this paper we consider the use of Gamma Ray Bursts (GRBs) as distance
markers to study the unification of dark energy and dark matter in the context
of the so-called Generalized Chaplygin Gas (GCG) model. We consider that the
GRB luminosity may be estimated from its variability, time-lag, and also use
the so-called Ghirlanda relation. We evaluate the improvements one may expect
once more GRBs and their redshift become available. We show that although GRBs
allow for extending the Hubble diagram to higher redshifts, its use as a dark
energy probe is limited when compared to SNe Ia. We find that the information
from GRBs can provide some bounds on the amount of dark matter and dark energy
independently of the equation of state. This is particularly evident for
XCDM-type models, which are, for low-redshifts ($z\leq2$), degenerate with the
GCG.
