With the cutie marks being smaller and hard to see in the G5 movie, and no attention being paid to them in the plot or dialog, I think we all got the feeling that G5 was going to mostly ignore cutie marks altogether.
I just caught one of the new G5 YouTube shorts which showed Hitch giving a tour of Mareitime Bay. The footage zoomed in on Zipp's cutie mark while she was having fun on a rope climbing course, and her cutie mark began to glow. This is the first I've seen of G5 paying any attention at all to cutie marks, so I was intrigued.
There doesn't seem to be an obvious connection between what she was doing and why her cutie mark was glowing (maybe they glow when the pony is especially happy or doing a skill they are particularly good at?) but this might be something that gets explored in future shorts or the new upcoming series.
I'm curious, has there been any other cutie mark references in G5 media, like are they mentioned on the backs of the toy boxes or in any of the books?