A bit ago I wrote about stacks on Awn well now it's been slightly updated. It looks nicer and has some nice new features but it is still a little buggy.
As you may be able to see, you con now better see multiple icons of things from in your stack. I have a pdf text document then a patch and then the Google image from the Google homepage. And you can pretty much see all of them. From my own tests it seems like it shows you the last 3 things put into your stack.
More Here