The process took 2 weeks. I interviewed at 3M (Minneapolis, MN) in Jan 2011
Interview
2 on-campus interviews. First was 1:1 behavioral and case-based. Cases were more like short-answers than a full blown case interview. Second was a full case and was with two members from the company. Cases were about products at the company and based on marketing mix type questions. Overall it was a pretty fun series of interviews. I kept getting dragged on through the follow-up process and ultimately never heard back from the company. Kind of annoying...
Interview questions [1]
Question 1
Tell me about a time you encountered a barrier and had to overcome it
The process took 1 day. I interviewed at 3M (Saint Paul, MN) in Oct 2011
Interview
I went in to an on-campus interview. I went to a pre-night where three employees/interviewers gave a presentation on the interview and internship process at 3M. Although the interview wasn't extremely hard, they did ask questions that kept me on my toes. Make sure you are up-to-date on all of the companies operations.