  Isolated neutron stars undergoing non-radial oscillations are expected to
emit gravitational waves in the kilohertz frequency range. To date, radio
astronomers have located about 1,300 pulsars, and can estimate that there are
about 2 times 10^8 neutron stars in the galaxy. Many of these are surely old
and cold enough that their interiors will contain matter in the superfluid or
superconducting state. In fact, the so-called glitch phenomenon in pulsars (a
sudden spin-up of the pulsar's crust) is best described by assuming the
presence of superfluid neutrons and superconducting protons in the inner crusts
and cores of the pulsars. Recently there has been much progress on modelling
the dynamics of superfluid neutron stars in both the Newtonian and general
relativistic regimes. We will discuss some of the main results of this recent
work, perhaps the most important being that superfluidity should affect the
gravitational waves from neutron stars (emitted, for instance, during a glitch)
by modifying both the rotational properties of the background star and the
modes of oscillation of the perturbed configuration. Finally, we present an
analysis of the so-called zero-frequency subspace (i.e. the space of
time-independent perturbations) and determine that it is spanned by two sets of
polar (or spheroidal) and two sets of axial (or toroidal) degenerate
perturbations for the general relativistic system. As in the Newtonian case,
the polar perturbations are the g-modes which are missing from the pulsation
spectrum of a non-rotating configuration, and the axial perturbations should
lead to two sets of r-modes when the degeneracy of the frequencies is broken by
having the background rotate.
