  We report the discovery of burst oscillations at 414.7 Hz during a
thermonuclear X-ray burst from the low mass X-ray binary (LMXB) 4U 0614+091
with the Burst Alert Telescope (BAT) onboard SWIFT. In a search of the BAT
archive, we found two burst triggers consistent with the position of 4U
0614+091. We searched both bursts for high frequency timing signatures, and
found a significant detection at 414.7 Hz during a 5 s interval in the cooling
tail of the brighter burst. This result establishes the spin frequency of the
neutron star in 4U 0614+091 as 415 Hz. The oscillation had an average amplitude
(rms) of 14%, These results are consistent with those known for burst
oscillations seen in other LMXBs. The inferred ratio of the frequency
difference between the twin kHz QPOs, and the spin frequency in this source is
strongly inconsistent with either 0.5 or 1, and tends to support the recent
suggestions by Yin et al., and Mendez & Belloni, that the kHz QPO frequency
difference may not have a strong connection to the neutron star spin frequency.
