I had my interview earlier today. The admissions office gave me a t-shirt and a folder containing some information on my post MBA career path and clubs I mentioned in my application. Like the folder, the interview was tailored to my application materials. I won't get into specific questions (you can use ClearAdmitWiki), but I would tell you to review your essays and know your story well. Go over the questions you have already asked yourself 100 times - why MBA, why Stern, what clubs do you want to participate in, how will you reach your career goals, etc. Also, know your professional/personal strengths and what you will bring to Stern.
Overall, the experience was very pleasant. For those of you that haven't visited Stern yet, the admissions staff is very nice and welcoming. The interview was 1-on-1 for about 35-40 minutes. I had a chance to ask some questions at the end, so prepare a couple. If anyone wants more info, PM me.