I recently changed my settings on my Multiply Inbox so that I'd be shown updates by contacts of my contacts. The overwhelming majority of these updates were music playlists, a whole lot of music in fact. All of the ones that I checked were visible to me on each user's page, and all appeared with a "Download" link next to them on each user's page.
I hate to be a party pooper but this basically offers a way to share copyright protected music. Anyone with access to the playlist can simply download the song from your page. Aside from potentially violating the Digital Millennium Copyright Act it's also a clear violation of the Multiply Terms of Service and Use, the penalty for which can be the termination of your Multiply account. I asked Multiply customer service for clarification and received the following as part of their reply, "sharing unauthorized copyrighted material (including music) violates our terms. So yes, you can share music, as long as it is not unauthorized copyrighted music."
You may want to make all of your playlists private, just to be safe. Edit each playlist, select the "Advanced" access option then uncheck all of the boxes and save. Each playlist will state "For you" in the upper right corner once you've properly edited it.
Given the increasingly litigated legal issues surrounding music I suspect that the abilities to download, embed and/or share music will soon be severely limited.
This concludes this public service announcement, we now return to your regularly scheduled multiplying.