Hmm...
1) The request Frog made I am sure was for extracting images from inside RAR-archives and burning them on-the-fly, not burning the RAR-archives... (so I don't get what difference it would make if there were any players that would play RAR:ed ISO:s or not?)
2) As far as software media players, VLC, for one, plays mpeg2-streams from inside RAR-archives, if that makes any difference.
I would love to be able to burn straight from RAR:s, so add me to the list of requestors.