Half the time when I download a .sit file, all the files in the unpacked directory are invisible to the finder (though they show up with "ls".) They're not dot files. Neither "/Developer/Tools/SetFile -a v dir/*" nor "/Developer/Tools/SetFile -a V dir/*" makes them show up in the finder.
Making a new directory and "cp -pr" makes them show up. Uh, I think? Usually? But is there some easier way than that?
Update: StuffIt is confusing Finder. Restarting Finder after un-stuffing makes the files show up. Stupid StuffIt.
Update 2: Creating a new sub-folder of the folder with the invisible files also seems to un-confuse Finder. Stupid StuffIt.