  We summarize some recent ideas relating to anisotropic particle production in
high-energy collisions. Anisotropic gluon distributions lead to anisotropies of
the single-particle azimuthal distribution and hence to disconnected
contributions to multi-particle cumulants. When these dominate, the
four-particle elliptic anisotropy $c_2\{4\}$ changes sign. On the other hand,
connected diagrams for $m$-particle cumulants are found to quickly saturate
with increasing $m$, a ``coherence'' quite unlike conventional ``non-flow''
contributions such as decays. Finally, we perform a first exploratory
phenomenological analysis in order to estimate the amplitude ${\cal A}$ of the
$\cos(2\varphi)$ anisotropy of the gluon distribution at small $x$, and we
provide a qualitative prediction for the elliptic asymmetry from three-particle
correlations, $c_2\{3\}$.
