I forwarded Kurt Swanson's Scandinavian/Chinese MIME test message to my work account (where I use Lotus Notes 4.6a to read mail), munging the headers a bit as I did so in order to make sure I could actually see the MIME as Lars sent it.  Here's what I got.

Each of the horizontal thick black bars is left-clickable, and brings up a pop-up dialog showing the type of that part: "text/plain; charset=iso-8859-1" for the first bar, "text/plain; charset=cn-gb-2312" for the second bar, "text/plain; charset=iso-8859-1" for the third bar.