Version:            (using KDE KDE 3.3.0)
Installed from:    Gentoo Packages

The icon indicating that a folder is shared (a plug) is not very intuitive. I'm not sure what an intuitive one would look like (after thinking about this I realised that the windows icon (the hand) isn't any better).
But I've seen the icon come up for months and always boggled as to what it meant. It only discovered the answer, when one day going through the control centre I clicked on the file sharing applet, and saw all my shares lined up with the icon next to each of them.

Perhaps the tool tip when holding the mouse over the directory could include a note like "this directory is shared via samba/nfs"?
Or the share tab for the directory's properties could show the icon (just the plug part, not the folder), along with "this directory is shared" (even if kde file sharing hasn't been configured), so that we know the icon is associated with sharing.