  The Far Ultraviolet Spectroscopic Explorer (FUSE) has observed over three
hundred fifty sightlines to extragalactic targets. About one hundred fifty of
these are of sufficient quality to measure OVI absorption in and near the Milky
Way. High-velocity OVI absorption is detected in about 80% of the sightlines,
with the detection rate going up for sightlines with higher signal-to-noise
ratios. OVI is almost always seen in directions with previously known HI HVCs,
including HVCs complex C, complex A, complex WD, the Magellanic Stream, and the
Outer Arm. Studies of several sightlines through complex C suggest that the OVI
absorption is produced in conductive interfaces between the cool HVC and a
hotter surrounding medium, most likely a corona around the Milky Way. The OVI
detections associated with the Magellanic Stream imply that this hot corona has
a radius of at least 50 kpc. About half of the detections of high-velocity OVI
are in directions where no high-velocity HI was previously known. Some of these
are probably associated with the Magellanic Stream, others may represent Local
Group gas. Still others often show up as a distinct wing on the low-velocity
absorption; these may either represent an outflow from the Milky Way associated
with the Galactic Fountain, they may be extragalactic HVCs, or they may be
tracing a wind from the Galactic Center. Distance limits to the high-velocity
OVI are scarce, but at least one of the clouds appear to be more distant than 4
kpc.
