The Adobe Illustrator Story is a great short documentary with a behind-the-scenes view of how the software came to be:
When Adobe Illustrator first shipped in 1987, it was the first software application for a young company that had, until then, focused solely on Adobe PostScript. The new product not only altered Adobe’s course, it changed drawing and graphic design forever.
Adobe Illustrator was the first design application I learned how to use, and my mind still works very much in line with how Illustrator works. Whether or not it was the countless hours I spent drawing curves one point at a time, learning Illustrator made me feel empowered by my computer. Like I was working with it, rather than trying to trick it into doing what I wanted.