  We investigate a possible nucleosynthetic signature of highly energetic
explosions of C-O cores ("hypernovae," HNe) which might be associated with
gamma-ray bursts (GRBs). We note that the direct impact of C- and O-enriched
hypernova ejecta on the ambient hydrogen and helium leads to spallation
reactions which can produce large amounts of the light nuclides lithium,
beryllium, and boron (LiBeB). Using analytic velocity spectra of the hypernova
ejecta, we calculate the LiBeB yields of different exploding C-O cores
associated with observed hypernovae. The deduced yields are $\sim 10^3$ times
higher than those produced by similar (direct) means in normal Type II
supernovae, and are higher than the commonly used ones arising from shock wave
acceleration induced by Type II supernova (SN) explosions. To avoid
overproduction of these elements in our Galaxy, hypernovae should be rare
events, with $\la 10^{-3}$ hypernovae per supernova, assuming a constant HN/SN
ratio over time. This rate is in good agreement with that of long duration GRBs
if we assume that the gamma-ray emission is focussed with a beaming factor
$\Omega/4\pi \la 10^{-2}$. This encouraging result supports the possible HN-GRB
association. Thus, Galactic LiBeB abundance measurements offer a promising way
to probe the HN rate history and the possible HN-GRB correlation. On the other
hand, if hypernovae are associated to very massive pregalactic stars
(Population III) they would produce a LiBeB pre-enrichment in proto-galactic
gas, which could show up as a plateau in the lowest metallicities of the Be-Fe
relation in halo stars.
