  For systems of two and three spins 1/2 it is known that the second moment of
the Husimi function can be related to entanglement properties of the
corresponding states. Here, we generalize this relation to an arbitrary number
of spins in a pure state. It is shown that the second moment of the Husimi
function can be expressed in terms of the lengths of the concurrence vectors
for all possible partitions of the N-spin system in two subsystems. This
relation implies that the phase space distribution of an entangled state is
less localized than that of a non-entangled state. As an example, the second
moment of the Husimi function is analyzed for an Ising chain subject to a
magnetic field perpendicular to the chain axis.
