--the 'already-downloaded icon' doesn't pick up on tunes that get sent to the shared iTunes folder if they are manually deleted from the unshared dl folder . (Roger--I don't work with iTunes much, so this is likely to be a new user problem. Otherwise, I was impressed by how well LW integrates with iTunes). I guess keeping the Library updated is in the future plans. The recognition of files in the unshared folder does work well--thanks for that.
It depends how iTunes is configured ("Copy files to iTunes Music folder when adding to library" or not - former is default) and if you delete the tune from your shared directory then LimeWire is no longer aware of it (iTunes holds an own copy of it, see the above setting) and it's therefore a new file at the next search from LW's perspective.
Edit: and the future is close.