  We present the first dedicated observations of Interplanetary Scintillation
(IPS) with the Murchison Widefield Array (MWA). We have developed a synthesis
imaging technique, tailored to the properties of modern "large-N" low-frequency
radio telescopes. This allows us to image the variability on IPS timescales
across 900 square degrees simultaneously. We show that for our observations, a
sampling rate of just 2Hz is sufficient to resolve the IPS signature of most
sources. We develop tests to ensure that IPS variability is separated from
ionospheric or instrumental variability. We validate our results by comparison
with existing catalogues of IPS sources, and near-contemporaneous observations
by other IPS facilities. Using just five minutes of data, we produce catalogues
at both 79MHz and 158MHz, each containing over 350 scintillating sources. At
the field centre we detect approximately one scintillating source per square
degree, with a minimum scintillating flux density at 158MHz of 110mJy,
corresponding to a compact flux density of approximately 400mJy. Each of these
sources is a known radio source, however only a minority were previously known
to contain sub-arcsecond components. We discuss our findings and the prospects
they hold for future astrophysical and heliospheric studies.
