  We present a detailed description of the dynamics of the magnetic modes in
the recently discovered superconducting pnictides using reliable
self-consistent spin-wave theory and series expansion. Contrary to linear
spin-wave theory, no gapless mode occurs at the N\'eel wave vector. We discuss
the scenario that the static magnetic moment is strongly reduced by magnetic
fluctuations arising from the vicinity to a quantum phase transition. Smoking
gun experiments to verify this scenario are proposed and possible results are
predicted. Intriguingly in this scenario, the structural transition at finite
temperature would be driven by an Ising transition in directional degrees of
freedom.
