  We address the shot noise in the tunneling current through a localized spin,
pertaining to recent experiments on magnetic adatoms and single molecular
magnets. We show that both uncorrelated and spin-correlated scattering
processes contribute vitally to the noise spectrum. The spin-correlated
scattering processes provide an additional contribution to the
Landauer-B\"uttiker shot noise expression, accounting for correlations between
the tunneling electrons and the localized spin moment. By calculating the Fano
factor, we show that both super- and sub-Poissonian shot noise can be described
within our approach. Our theory provides transparent insights to noise
spectroscopy, consistent with recent experiments using local probing techniques
on magnetic atoms.
