I first was interviewed over the phone for about an hour and a half. I was asked a variety of technical questions, little if any behavioral. I was asked to describe my Ph.D. research and asked questions about it. By the end of the phone call I was schedule for an on-site interview. Intel made the flight/hotel/car very painless and they even paid for a few extra days for me to check out the city.
The on-site interview consisted of 10 45-minute interviews scheduled back-to-back, with a break for lunch. I also delivered an hour long research presentation. The questions I asked were generally technical in nature, or about how I liked to deal with conflict and stress. They were also very upfront about the less desirable parts of the job I interviewed for.
The people I talked to were generally quite friendly and I came away with a really good impression of company culture. Everyone dressed in jeans and button up or polo shirts.