  We discuss the impact of recent high-statistics RHIC data on the
determination of the gluon polarization in the proton in the context of a
global QCD analysis of polarized parton distributions. We find clear evidence
for a non-vanishing polarization of gluons in the region of momentum fraction
and at the scales mostly probed by the data. Although information from low
momentum fractions is presently lacking, this finding is suggestive of a
significant contribution of gluon spin to the proton spin, thereby limiting the
amount of orbital angular momentum required to balance the proton spin budget.
