I was contacted by a recruiter on Linked-In. I usually ignore these requests, but the Palantir recruiter actually contacted me twice, which made me take a look at their company. The company seemed like a great place to work—strong company culture, great compensation/perks, and a company mission that seemed to take ethical considerations very seriously.
I contacted the recruiter via Linked In, who set up and initial phone screening within a week. During the phone screening, she described the three available positions (in McClean, VA), and asked a few quick technical questions (anybody with a four-year computer science degree should have been able to answer them). All in all, the screening lasted about 20 minutes.
Afterwards, she set me up for a phone interview with another Forward-Deployed Engineer in McClean and sent me some material to review. (I highly recommend looking over the material and researching the company before going through the interview.) That interview took about an hour, and seemed very casual. The interviewer asked a few technical questions (one on Linux, one programming question), asked me to describe my experience and expertise, and let me ask him a few questions about the company. (From what I understand now, every Palantir employee is required to conduct interviews, so my interviewer was by no means a professional H.R. representative, and he seemed more nervous for the interview than I did.)
Afterwards, I was invited to interview at the Palo Alto (Silicon Valley) office. Palantir offered to fly me there and would pay for a nice hotel. At this point, however, I decided to withdraw my application (see below). Overall, I felt it to be a very positive interview process, but Palantir just wasn't the company for me.