  It is shown that the interplay of long-range disorder and in-plane magnetic
field gives rise to an out-of-plane spin polarization and a finite spin Hall
conductivity of the two-dimensional electron gas in the presence of Rashba
spin-orbit coupling. A key aspect is provided by the electric-field induced
in-plane spin polarization. Our results are obtained first in the
\textit{clean} limit where the spin-orbit splitting is much larger than the
disorder broadening of the energy levels via the diagrammatic evaluation of the
Kubo-formula. Then the results are shown to hold in the full range of the
disorder parameter $\alpha p_F \tau$ by means of the quasiclassical Green
function technique.
