This page was posted in response to a user who reported that in Illustrator CS Pathfinder Divide would not create a closed shape out of overlapping open paths, trimming off the ends, like it would in Illustrator 9. I made the page not to show how to do something, but to demonstrate that AI 9 and AI CS were both doing the same thing. The distinction is not between the two versions, but whether the open paths have a fill color or not. When using AI 9, his paths were unfilled, and when using AI CS, they had white fills.

Illustrator 9 (unfilled paths)

Illustrator CS (unfilled paths)

Illustrator 9 (filled paths)

Illustrator CS (filled paths)