  The Casimir--Polder interaction between an anisotropic particle and a surface
is orientation dependent. We study novel orientational effects that arise due
to curvature of the surface for distances much smaller than the radii of
curvature by employing a derivative expansion. For nanoparticles we derive a
general short distance expansion of the interaction potential in terms of their
dipolar polarizabilities. Explicit results are presented for nano-spheroids
made of SiO$_2$ and gold, both at zero and at finite temperatures. The
preferred orientation of the particle is strongly dependent on curvature,
temperature, as well as material properties.
