  Motivated by recent interest in novel spintronics effects, we develop a
semiclassical theory of spin transport that is valid for spin-orbit coupled
bands. Aside from the obvious convective term in which the average spin is
transported at the wavepacket group velocity, the spin current has additional
contributions from the wavepacket's spin and torque dipole moments. Electric
field corrections to the group velocity and carrier spin contribute to the
convective term. Summing all terms we obtain an expression for the intrinsic
spin-Hall conductivity of a hole-doped semiconductor, which agrees with the
Kubo formula prediction for the same quantity. We discuss the calculation of
spin accumulation, which illustrates the importance of the torque dipole near
the boundary of the system.
