Here it goes again. And sorry for the delay, I was busy with other things, will catch up...
Yes, I believe it does not conflict with the savefig's landscape-vs-portrait handling. Some of the EPS viewers need this flag in order to show the plot in its original orientation (read: heads up).
In addition, I find the code in lines 1049-1053 of bakend_ps.py somewhat strange: in my understanding, landsape means that the plot's "up" direction is oriented to the left, i.e., the plot is rotated 90CCW. This has nothing to do with the plot's width and height. However, that's not my code I wouldn't like to fix that myself without knowing the original author's intent. Comments?
RCS file: /cvsroot/matplotlib/matplotlib/lib/matplotlib/backends/backend_ps.py,v
retrieving revision 1.81
diff -r1.81 backend_ps.py
> print >>fh, "%%Orientation: Portrait"