I think this is a 7.5 feature, but I noticed, that now if you try to add a song to a playlist twice, iTunes will warn you and let you know that you already have the song in the playlist. This is a great feature for me, as I create large playlists for my road trips, and I’ve noticed every now and then that I have the same song twice or sometimes even thrice in there. So, Yay NoDupes!!!