It's called Dryfix foam by Everbuild. I had to take some reveals off on Friday that were stuck on with it and it took the skim off and I was back at the scratch coat. The problem with it is that when dabbing full boards you need to hold the boards in place until the foam has stopped expanding and properly set, which is only 10-15 mins, otherwise you end up with steps in the joints. When i've used it, I have put in a few screws/plugs to keep the board where I want it.
The stuff is good for small areas and for sticking to painted surfaces. That's about it.