We comment on the first indication of geo-neutrino events from KamLAND
and on the prospects for understanding Earth energetics. Practically
all models of terrestrial heat production are consistent with data
within the presently limited statistics, the fully radiogenic model
being closer to the observed value ($\approx 9$ geo-events). In a few
years KamLAND should collect sufficient data for a clear evidence of
geo-neutrinos, however discrimination among models requires a detector
with the class and size of KamLAND far away from nuclear reactors. We
also remark that the event ratio from Thorium and Uranium decay chains
is well fixed $N(Th)/N(U) \simeq 0.25$, a constraint that can be
useful for determining neutrino oscillation parameters. We show that a
full spectral analysis, including this constraint, further reduces the
oscillation parameter space compared to an analysis with an energy
threshold $E_{vis}>2.6 MeV$.
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