The process was very nice. I met with an engineer at my school's career fair and handed them my resume. After two days, I got an email from a recruiter telling me that they wanted to set me up with an interview on my campus. They also invited me to a dinner with the other students that they got in touch with, which was nice. The interview at my school was a 45-minute interview where they asked me one technical question. It went well and the interviewer was very nice.
After that interview, I heard back within two days that they wanted to move forward. I was then able to schedule an interview on-site at their office in Menlo Park. When it was time, they flew me out to Menlo Park for Facebook University Day. I had one 45-minute interview in the morning, followed by a full day of getting to see what Facebook had to offer, including a tour of the office.
The on-site interview was the final stage of the process for interns. They sent me their final decision within a week.