Today's beta version brings the ability to render walls, floors and ceilings either as matte (the default), or as shiny, with new radio buttons added to Wall and Room dialogs.





As these options are available for each wall and each room, you'll be able to mix shiny and matte surfaces in your home if needed.
At this time, shiny surfaces are rendered with SunFlow shiny shader but I'd try to replace it by Uber shader, once I find a way to avoid the white spots experienced by fhoofman and others.