yes, there's a tag-based playlist system -- just favorite a song to begin.
Oh okay I think I finally worked it after toying with things off and on over 20 minutes - a "tag radio" list has appeared when I'm in a radio section and if I click one of those tags music will play continuously. I guess by playlists I meant ones I create.
In any case I think this feature needs to be a lot clearer.
I think you're on the home page. For an example, you can see my personal tag playlist named 'mellow':