From the article above is this:
"In this article I'll explain what's needed to achieve editable layers in Photoshop from your Illustrator artwork and call out some of the pitfalls to look for along the way. There is one thing to note before we get underway: Although this discussion relates to the most recent versions of Illustrator and Photoshop (10 and 7, respectively), these capabilities originally found their way into Illustrator 9 and Photoshop 6 and should be relevant to users of these versions as well."
I wouldn't know much about previous versions though, only what I have now which is AI CS and PS CS2.