  State reconstruction for quantum spins is reviewed. Emphasis is on
non-tomographic approaches which are based on measurements performed with a
Stern-Gerlach apparatus. Two consequences of successfully implemented state
reconstruction are pointed out. First, it allows one to determine
experimentally the expectation value of an arbitrary operator without a device
measuring it. Second, state reconstruction suggests a reformulation of
Schroedinger's equation in terms of expectation values only, without explicit
reference to a wave function or a density operator.
