But if you prefer the Grid mode's method not opening folders unless commanded, you might like today's hint, courtesy of arcticmac. After implementing today's hint, when you open a List mode Stack in Snow Leopard, it will look like a vertical version of a Grid mode Stack.
Instead of having folders that open in slide-out folders, as in the left-hand side of the above image, folders won't expand until you click the mouse (or press Return) with a folder highlighted. When you do open a folder, its contents will replace the current folder's contents, which is how Grid-mode Stacks work, too; a small arrow at the top will let you navigate back up to the parent folder (or you can press Command-Up Arrow).
(If you're wondering, this hint coexists nicely with that explains how to always see a mouseover highlight effect in Snow Leopard's Stacks.)
To make this change on your Snow Leopard machine, open Terminal (in Applications -> Utilities) and enter these two commands, pressing Return after each one.
defaults write com.apple.dock use-new-list-stack -bool YES