Comment 7 for bug 347784

If I'm playing last.fm in Rhythmbox, then I double click on an empty (non-last.fm) playlist the music stops, but if I double click on last.fm again it starts back up where it was. Obviously pausing is possible. The point that Last.fm doesn't allow it on the website though is

As for the other things, internet radio has to follow certain legislation (DMCA) and court rulings (http://www.broadcastlawblog.com/tags/internet-radio-fees/) regarding interactivity. Internet radio stations already have to pay general licensing fees to play music at all (unlike regular radio), and if they are "interactive" (ie. let people specifically choose the songs they want to hear and when to hear them) then they must negotiate/pay licensing fees individually for each song. Apparently replaying a song, or being able to skip ahead indefinitely is considered too much control.

Look at Pandora, for instance. Even paid subscribers have a limit to how many songs they can skip in a given period, and can never go back/replay a song.