@Sudhir Jain is right. I was told decisions will be out April 15th as well.
For those who have not done the interview yet, it didn't turn out to be that unusual after all in my opinion. There will be some standard questions (Why IDM? Some digging into/questions about your portfolio, time to ask them questions, etc.) and some unusual questions. But the unusual questions are just abstract questions designed to test your imagination that are quite fun, and for which there isn't any right or wrong answer. You can't really prepare for them, but if you are wondering, they are questions along the lines of "If you were a fish, how would you feel?" [just an example, not the exact question you will get asked.]
Just have fun and relax!