A group of Product Designers came to my school and I got the chance to get my Portfolio reviewed by one of the Designers, she liked my work and few days later I got an e-mail asking if I would be interested in a formal job interview with Facebook. It was a two-hour phone interview with to different Product Design Managers. First interview was about my own work, and the key there is to know the in and outs of your work, you have to be able to defend all your design choices. Second interview was about a random Mobile Application, I got the Twitter Mobile Application, the key here is to come up with a solution for some of the features, or missing features, and backup your possible solution with data. Here they are really trying to find out how you think, and how good you are finding multiple solutions to a certain problem.

Straightforward like any big tech interview, but long and intense. Formats are pretty standardized so it just takes practice. Questions appear like it's from a bank, so if you're prepared you should be fine.