Apple music-centered social network "Ping," has received an update that now let you create playlists of your favorite songs. You can make those public to your Ping followers, who in turn can then rate or review any of your public playlists, and, even collaborate on public playlists with you.
"To create a playlist, click the Ping icon in the iTunes sidebar, and go to your profile page. Then look for Playlists section on the right side and click 'Create a New Playlist'. Once there, you can give your playlist a title, a description, and perhaps tick the aforementioned 'Allow people who follow me to add songs' option if you so wish. Songs can be reordered at any time, even after you've made your playlist public. You can also import an existing iTunes playlist by simply clicking its title, then the arrow icon, and in the dialog box that appears, selecting 'Publish playlist'.
The songs inside a playlist can only come from the iTunes store. There's absolutely no support for adding your own MP3 collection, but that's to be expected from Apple."