I applied for Internship Program, presenting myself as Front-End Developer, via Carreer section on Palantir Website in January 2014. After a week, they replied with coding challenge, that consisted of one quite simple probem with time limited to 100 min. I felt confident after taking this challenge, and after 3 days, they offered Phone screen. I was in the middle of my finals, so asked for 2 weeks, and there was no problem with scheduling, recruiter was really nice and replied within minutes.
Phone screen was led by an engineer, but unfortunately, in first seconds first problem appeared - voice quality was horrible, but since I'm from Europe, that's probably the reason. If you are from Europe, try to ask for other possibility like VoIP, Skype,.. In first part, the engineer described his position (he was also Front-End Dev. so they probably matched it with my preferences), then started with set of problems, They were really easy, like finding duplicates in array of integers. I screwed one variation to this problem (finding duplciated only within k sequential indices). In the end, i had time for two question. Over all, the engineer was really nice, trying to give me some hints etc. Whole interview lasted 45 minutes.
Well, I didn't do well, so after 3 days i recieved declining email.
To sum up - there was really no problem in communication. But since Palantir hires the best of the bests, once you fail a bit, u are out of hiring proccess, so be prepared!