A group of engineers came to my school for two days to conduct interviews. I had an initial, on-campus screening interview that lasted about 45 minutes. The interviewer asked me to elaborate on some of the projects on my resume; he then asked me a few behavioral-type questions like, "Tell me about yourself" and "Describe a time you had an altercation with a teammate and how'd you handle it."
About two weeks later, I was asked to fly out to Pasadena for an on-site interview. In the morning, the HR department gave a presentation on the hiring process and the benefits of working at JPL. I then had three 30-45 minute 1-on-1 interviews with managers and supervisors; then I gave a one hour presentation on a project I had worked on. After the presentation, I had lunch with a few early-career employees and then I went on a tour. I finished off with four more 1-on-1 interviews.
Overall, it was a very enjoyable process. The on-site interviews were all about the same as the screening interview; just a few behavioral questions and then they ask you questions about your resume. The interviewers spent a lot of time talking about what their group does. Everyone was very friendly and personable.