I submitted my resume through a current employee, and was invited to the monthly group interview. The first hour (as stated below) was a case study, which wasn't too bad (just a lot of writing, a little stressful, and with no feedback). The second two hours were team-based problem solving games & puzzles, designed to see how you work with people. It was actually kind of fun. There were observers the entire time, but it was easy to focus on the tasks & forget they were there.
The group (there were 11 of us) then were treated to lunch, and let to wait in a conference room for an hour while the observer team deliberated. (The comparison to American Idol Hollywood Week cracks me up--it's so true!) At the end of the hour, the IS director came in, thanked everyone for participating, and announced who would be staying for continued interviews (1 out of the 11).
I was the one. I then went up to the PMO for two interviews--one with a few team members, one with the IS director. They were enjoyable conversations, but clearly focused on my preparation & knowledge. This took another 90 min or so--all told, I was onsite for 6.5 hours.
I interviewed on a Friday, and received word on Monday morning that I wasn't judged to be a good fit for their needs, and would progress no further.