Went to an on-campus recruiting presentation for the company in the beginning of November. I applied for the position the following day on the JPM Careers website; two days later I received a call from the recruiter about setting up a phone interview (he wanted to do it the following day, but I wasn't available until early the next week). Participated in the phone interview: it wasn't very hard, lots of questions can be found by reviewing the JPM Careers website so I was well prepared. Interview lasted 30 minutes, and two days later I received an email invitation for an Interview "SuperDay" at one of their offices.
The SuperDay was a half-day event consisting of an introductory time period with the HR staff and recruiter, two interviews with VP-level employees, a short break, and a group activity. My interviews happened to be back to back, and lasted exactly 30 minutes (we were stopped at the half-hour mark). The interviewers were very nice and personable, but you could tell they didn't do them all the time as they worked off a template of pre-provided questions. However, I got along well with both of them very well, and by the end of the interview we were having a completely off-topic discussion. The group activity at the end was for all the applicants (there were six of us total) to participate in a puzzle/trivia exercise in front of the interviewers, and the recruiter & HR reps. It was difficult, and meant to judge your problem-solving ability, as well as to see how you work with others in a team.
After the activity, we were ushered out of the building by one of the HR reps (she was really nice!), and told to expect an answer in about 10 days. My interview happened to be a week before Thanksgiving, which delayed my offer letter until about 2 weeks after the SuperDay (which was still a reasonable time).
Overall, it was a great experience and I'm excited to begin the position.