  We consider quantum systems composed of $N$ qubits, and the family of all
Bell's correlation inequalities for two two-valued measurements per site. We
show that if a $N$-qubit state $\rho$ violates any of these inequalities, then
it is at least bipartite distillable. Indeed there exists a link between the
amount of Bell's inequality violation and the degree of distillability. Thus,
we strengthen the interpretation of Bell's inequalities as detectors of useful
entanglement.
