I wonder if there is a list somewhere around Apple of "Annoying Edge Cases We'd Have To Support If Smart Folders Worked At The Filesystem Level", and how long it is.
Like, you're in a smart folder that contains files whose name includes "foo", and you try to create a file whose name does not include "foo", what happens? Do you get an existing filesystem error? Do you get a new "can't create new files in smart folders" error?
Interestingly enough I just discovered that if you drag a file into the Tags section of the Finder window's sidebar, it will remain where it is - but if you create a smart folder whose criteria is "tag:tagname" it won't let you drag anything into it, even though it shows the exact same set of files.
