Let $M$ be the unit tangent bundle of a compact manifold
with negative sectional
curvatures and let $\hat M$ be a $\mathbb Z^d$ cover for
$M$. Let $\mu$ be the measure of maximal entropy for
the associated geodesic
flow on $M$ and let $\hat\mu$ be the lift of $\mu$ to
$\hat M$.
We show that the foliation $\hat{M^{s s}}$ is ergodic with
respect to $\hat\mu$.
(This was proved in the
special case of surfaces by Babillot and Ledrappier by
a different method.)
Our method
extends to certain Anosov and hyperbolic flows.