  We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield
Array 32-element prototype covering 2400 square degrees. The survey has a 15.6
arcmin angular resolution and achieves a noise level of 15 mJy/beam. We
demonstrate a novel interferometric data analysis that involves calibration of
drift scan data, integration through the co-addition of warped snapshot images
and deconvolution of the point spread function through forward modeling. We
present a point source catalogue down to a flux limit of 4 Jy. We detect
polarization from only one of the sources, PMN J0351-2744, at a level of 1.8
\pm 0.4%, whereas the remaining sources have a polarization fraction below 2%.
Compared to a reported average value of 7% at 1.4 GHz, the polarization
fraction of compact sources significantly decreases at low frequencies. We find
a wealth of diffuse polarized emission across a large area of the survey with a
maximum peak of ~13 K, primarily with positive rotation measure values smaller
than +10 rad/m^2. The small values observed indicate that the emission is
likely to have a local origin (closer than a few hundred parsecs). There is a
large sky area at 2^h30^m where the diffuse polarized emission rms is fainter
than 1 K. Within this area of low Galactic polarization we characterize the
foreground properties in a cold sky patch at $(\alpha,\delta) =
(4^h,-27^\circ.6)$ in terms of three dimensional power spectra
