Pardon the simple question, but what types of Object are supported as the source for a PictureMarkerSymbol? The 3.1 reference pages aren't very specific.
http://resources.arcgis.com/en/help/...erSymbol%28%29
http://resources.arcgis.com/en/help/...ol.html#source
http://resources.arcgis.com/en/help/...erSymbol%28%29
http://resources.arcgis.com/en/help/...ol.html#source