The process took 1 day. I interviewed at NVIDIA in May 2009
Interview
There was one phone screen only, and I was interviewed by a person from the team who was interested in hiring an intern (the video drivers group). They found me through campus recruiting, and scheduled me for a phone screen. It wasn't very formal, and it felt like the interviewer didn't really have a coding question fully prepared--he was just asking general topics to start a discussion and see where I would go.