I applied for the position when Facebook was interviewing on campus. Emailed my resume on the deadline, called up for interview within 5 days. After passing the first interview, I was informed that evening that I had a second interview the next day. After that, it was about a week or so before I heard back, and since I was a graduate student the third and last stage was to match me with a particular group. Within a few days of the matching process (done via phone) I received my offer letter. The two on-campus interviews consisted of writing down actual code (in my case, I used Java) and they were fairly basic and specific data structures related questions.