This doesn't work at all. Whatever radio stream I try to play, a window appears saying some components are needed (text/html), but in the box below that where the necessary components are supposed to be listed and downloadable, it's blank. In the discussion area of the Real site, a staff person posted instructions (from Oct. 2008) for what to do to fix this, but they didn't help.
There are fewer and fewer radio streams that are not playable in iTunes. Good thing!