  We perform magnetohydrodynamic simulations in full general relativity (GRMHD)
of quasi-circular, equal-mass, binary neutron stars that undergo merger. The
initial stars are irrotational, $n=1$ polytropes and are magnetized. We explore
two types of magnetic-field geometries: one where each star is endowed with a
dipole magnetic field extending from the interior into the exterior, as in a
pulsar, and the other where the dipole field is initially confined to the
interior. In both cases the adopted magnetic fields are initially dynamically
unimportant. The merger outcome is a hypermassive neutron star that undergoes
delayed collapse to a black hole (spin parameter $a/M_{\rm BH} \sim 0.74$)
immersed in a magnetized accretion disk. About $4000M \sim 60(M_{\rm
NS}/1.625M_\odot)$ ms following merger, the region above the black hole poles
becomes strongly magnetized, and a collimated, mildly relativistic outflow ---
an incipient jet --- is launched. The lifetime of the accretion disk, which
likely equals the lifetime of the jet, is $\Delta t \sim 0.1 (M_{\rm
NS}/1.625M_\odot)$ s. In contrast to black hole--neutron star mergers, we find
that incipient jets are launched even when the initial magnetic field is
confined to the interior of the stars.
