  The Ep,i - Eiso correlation is one of the most intriguing properties of GRBs,
with significant implications for the understanding of the physics and geometry
of the prompt emission, the identification and investigation of different
classes of GRBs, the use of GRBs as cosmological probes. The Fermi satellite,
by exploiting the high accuracy of the GBM instrument in the measurement of Ep,
the simultaneous detection of GRBs with Swift, and the detection and
localization of GRBs in the GeV energy range by the LAT instrument, is allowing
us to enrich the sample of of GRBs with known redshift and reliable estimate of
Ep,i, and, thus, to further test the robustness, reliability and extension of
this correlation. Based on published results and preliminary spectral data
available as of the end of 2009, it is found that the locations in the Ep,i -
Eiso plane of Fermi long and short GRBs with measured redshift, including
extremely energetic events, are consistent with the results provided by
previous / other experiments.
