SilverWook said:

More pics.

http://www.ew.com/ew/gallery/0,,20647938_20695713,00.html?hpt=hp_t3

Bit of a tangent, but that link led me here: http://www.ew.com/ew/gallery/0,,20647938_20361457,00.html?stitched#20770650

It's a similar collection of pictures for the Empire book, but what's interesting is the specific picture. It's a picture of Irvin Kirshner's copy of an early version of the script, and what stuck out to me was the line where Yoda says "the tree, remember your failure at the tree." In the final movie, that line had the word "cave" instead of tree.

You're probably wondering what's so interesting about this, and here's the answer: there's a note in the annotated Heir to the Empire where Timothy Zahn talks about why he described the cave as having a tree growing out of the top of it. He says it was because the track on the soundtrack album used in that scene was "The Magic Tree," and he wanted to gracefully solve a discrepancy that had bugged him growing up listening to the album over and over again. Looks like we now finally have the real answer, which is that the title of the song is a holdover from an earlier version of the script.