  Magnetars are a sizable subclass of the neutron star census. Their very high
magnetic field strengths are thought to be a consequence of rapid (millisecond)
rotation at birth in a successful core-collapse supernova. In their first tens
of seconds of existence, magnetars transition from hot, extended
``proto-''magnetars to the cooled and magnetically-dominated objects we
identify $\sim10^4$ years later as Soft Gamma-ray Repeaters (SGRs) and
Anamolous X-ray Pulsars (AXPs). Millisecond proto-magnetar winds during this
cooling phase likewise transition from non-relativistic and thermally-driven to
magneto-centrifugally-driven, and finally to relativistic and Poynting-flux
dominated. Here we review the basic considerations associated with that
transition. In particular, we discuss the spindown of millisecond
proto-magnetars throughout the Kelvin-Helmholtz cooling epoch. Because of their
large reservoir of rotational energy, their association with supernovae, and
the fact that their winds are expected to become highly relativistic in the
seconds after their birth, proto-magnetars have been suggested as the central
engine of long-duration gamma ray bursts. We discuss some of the issues and
outstanding questions in assessing them as such.
