Saw this on ORD-DEN yesterday (UA 301, 12 June). When the FA came around with hot towels before landing, the basket had a cup of dry ice. It was a pretty cool effect, and the FA said they can put a lemon or some other scent in there to freshen up the F cabin. In fact the cabin did have a slight lemony fresh scent, although maybe I was imagining things. This was the first time I've seen this. Not a big deal, though, and I'd prefer to have my UA blankets back. Has anyone else experienced this yet?