I also am in Michigan, and working with MI GeoRef data is always a bit of a problem when I use QGIS and other programs that rely on GDAL/OGR conversion utilities. You might try EPSG:3078 as the source projection if it's the non-HARN MI GeoRef ("NAD 83/Michigan Oblique Mercator"), and EPSG:3079 as the source if it's the HARN version ("NAD 83(HARN)/Michigan Oblique Mercator") you want. These, to the best of my knowledge, are the "correct" EPSG codes to use as source projections representing the regular and HARN versions of NAD 83 MI GeoRef.
Having said that, my experience in using them in QGIS has been mixed. I often use the *.ecw aerials from Michigan CGI as the base image layer. QGIS support for *.ecw files is also somewhat shaky. Combining the two sometimes produces strange, skewed results.
Good luck, and please post a reply here if you succeed with EPSG 3078 and/or 3079 !
UPDATE 5:13 pm 19 Feb 11: Matt, if you try
ogr2ogr -a_srs EPSG:4326 [outputfile] [inputfile]
(i.e., leave out the "-s_srs" and "-t_srs" parameters and use "-a_srs" instead)
then the result plots (seemingly) correctly using QGIS, but then it won't work with any other layer. Sigh...