Phone screen with HR person, said hiring manager was out but would get back to me the following week. HR person called back within the promised time frame and set up an interview at HQ (which is gorgeous, btw).
Interview was with hiring (dept) manager and two would-be coworkers. All were very friendly and we seemed to hit it off well. They asked several questions gauging my experience with various technologies, my background, opinions on some technical subjects, etc. All told the interview lasted about a half hour total, and two things became very clear. One was that I would be a great fit personality-wise and culture-wise with their IT team. The other was that the job I thought I was applying for and the job they were trying to fill were two very different (though related) roles.
About a week or so later the HR person called and told me the hiring manager had reached the same conclusions I had, that it wasn't the right job, but said that they liked me and if a job opened up in the future that better fit what I was looking for, they'd love to bring me back in at that time. All in all it was a rather pleasant process and a nice company.