Coincidentally, I ran into some text on Wikipedia yesterday that gives a href="http://en.wikipedia.org/wiki/GNU_Free_Documentation_License">some interpretation by Richard Stallman of the "GNU Free Documentation License" (GFDL). I've seen miscellaneous other interpretations of the GPL attributed to him over the years. His opinion - whether you agree with it or not - has generally struck me as irrelevant from a legal point of view: lawyers have more expertise in this, and courts get the final say. So, the value of his opinion, if any, has seemed to me to be only that of a spiritual leader of his movement. The True Believers of any religion should, of course, carefully study and heed each word given to them by their prophet. Fortunately, with Stallman, and Apostle Eben Moglen still around, True Believers need not interpret things for themselves, as they necessarily must do in older religions.
For example, years ago when the license for Python 1.6 was being formulated, it was repeatedly revised in one section until Stallman declared it to be "GPL compatible". Since he's neither a lawyer or a court, I wondered why it mattered so much to Tim Peters (who, as in so many things, seemed to speak for Python's creator, Guido Van Rossum.) I eventually realized that Stallman's opinion was highly important in terms of swaying the True Believers - who Tim/Guido did not dare offend. And of course, on a more practical level, none of the conventional legal authority knew or cared anything about the situation, so perhaps Stallman was the highest available court to adjudicate the issue.