Heard about the opening through a friend. Loved the atmosphere and the people. They asked a lot of questions, and it was clear that they knew what they were looking for. My first interview was with the managers, and my second was with their group and the company president. I got the offer about a week later but was also asked to interview for a different opening. I returned to interview for the second opening. That was another two rounds, the second of which took four hours. I was given a choice between the two jobs and opted for the second. It has been a great experience.
Basically, they know exactly the kind of person they are looking for. A short interview with them is usually a bad sign. The interviews that last an hour or more are usually with candidates they like.