I assume by auto-expand you mean that you can see the entire name of a file without double clicking on the divider to expand it. I would also like to know this as I use column view most of the time and tend to have long file names.
If you're using Leopard, I don't think so. The book I have doesn't have anything to say about such an ability. One tip it has: Option-drag a divider, and all columns expand to show the longest file/folder name.