None yet, I'm afraid, although I'm writing a beets plugin to convert from pls to UPL and back. The problem with the plugin is that it's just not that useful unless you have a whole playlist manager to go along with it, which beets doesn't do very well right now. I'd be very happy if there was a player with good playlist management functionality that would support it, or that I could write support for, but I don't personally use any...