  We study the spin resonance peak in recently discovered iron-based
superconductors. The resonance peak observed in inelastic neutron scattering
experiments agrees well with predicted results for the extended $s$-wave
($s_\pm$) gap symmetry. Recent neutron scattering measurements show that there
is a disparity between longitudinal and transverse components of the dynamical
spin susceptibility. Such breaking of the spin-rotational invariance in the
spin-liquid phase can occur due to spin-orbit coupling. We study the role of
the spin-orbit interaction in the multiorbital model for Fe-pnictides and show
how it affects the spin resonance feature.
