I did one ages ago, not sure if its still valid. Apart from the usual, check models, chat etc, some of the group stuff I wasn't expecting.
Did a trapped in a desert style thing, where you had a certain list of items, and what was the best way to use them to survive. They where looking for good answers, mixed with your ability to communicate with the others and get your point accross.
I think its standard stuff, but something to be ready for. Need to show your confidence at that stage I'm reckoning, which back when I did it, I was slightly lacking, hence I failed to get a post.