  We explore large-scale cosmic structure using the spatial distribution of 542
gamma-ray bursts (GRBs) having accurately measured positions and spectroscopic
redshifts. Prominent cosmological clusters are identified in both the northern
and southern galactic hemispheres (avoiding extinction effects in the plane of
the Milky Way) using the Bootstrap Point-Radius method. The Northern Galactic
hemisphere contains a significant group of four GRBs in the redshift range 0.59
< z < 0.62 (with a Bootstrap probability of p = 0.012) along with the
previously-identified Hercules-Corona Borealis GreatWall (in the revised
redshift range 0.9 < z < 2.1, p = 0.017). The Southern Galactic hemisphere
contains the previously-identified Giant GRB Ring (p = 0.022) along with
another possible cluster of 7 - 9 GRBs at 1.179 < z < 1.444 (p = 0.031).
Additionally, both the Hercules-Corona Borealis Great Wall and the Giant GRB
Ring have become more prominent as the GRB sample size has grown. The approach
used here underscores the potential value of GRB clustering as a probe of
large-scale cosmic structure, complementary to galaxy and quasar clustering.
Because of the vast scale on which GRB clustering provides valuable insights,
it is important that optical GRB monitoring continue so that additional
spectroscopic redshift measurements should be obtained.
