When i did my interview (nov 2006) we had a panel of three in front. 1 HR chick and 2 controllers (instructors from the college) it was a purely behavioral type interview. With scenario based questions like - "in your previous work have you ever been faced with a situation where a colleague was doing something that was wrong/dangerous - what did you do about it?
Also i highly encourage everyone to get too a tower/centre - as they want you to know a fair bit about the job as well as show some motivation, ie you got off your butt and did some famil.