I'd like to hear more too. I did hear some info second-hand from a friend who had his Monday. Mine's next Monday so I'll be able to say more after that.
There are only 16 interviewed every week, which may explain why there isn't any feedback yet. Of those 16, my friend said ~13-14 of them were UW undergrads.
Other than that, he said it wasn't anything unusual, pretty standard questions, 2-on-1. He said someone gave a presentation and said last year they only accepted a handful (4 or 5 maybe) people in December, so hang tight.