Hi - I have been testing the out of the box gp print task with the Server 10.1, called from a flex viewer (version 3.3).
I am finding an issue with the output - the swatches in the printed legend are not rendered properly. See attached image below for an example - the legend swatches should be solid squares but instead they appear as a series of horizontal lines.
I remember encountering this error with arcgis server 10 (using arcpy.mapping), and sadly it does not appear to have been sorted at 10.1.