This was a fantastic book, read in one sitting.  I remember being taken with McCandless's idealism, but he also seemed terribly naive to me.  I've always though there must be some middle ground between rejecting the "cruel" world and totally, non-judgmentally embracing it. 

Since we'll go into the movie already knowing McCandless's fate, Penn will need to find poingnance and suspense in the details of how he gets there.  And while I think some of McCandless's escape was in itself a political act, the story really isn't.  Let's hope that folks on all sides of the "aisle" will be able to appreciate Penn's talent on this one.  To me, he seems to be an excellent choice make the film.