Started with a brief phone screen with HR, and scheduled an in-person interview in a week.
Once I arrived at the main lobby, the HR person walked me to the design/marketing building in the back of the large campus, then 4 groups of people came in to interview me. I presented my work to a design manager (who would be my peer), 2 copywriters, creative director (who joined the group less than 3 months ago), and VP of marketing. It took about 4 hours.
Despite the red brick buildings and the "hip" environment they're trying to create, the people were friendly but distant. I guess it makes sense for a company with 5,000+ people worldwide (and looking to hire more staff at the time).
One thing worth mentioning: After the interview, I wrote a thank you note to everyone I met, but no one replied except for the creative director. After I turned down the position, I wrote another email to thank everyone and wish them luck - again only one person wrote back. This isn't a big deal, but I believe it's an indication of team dynamics, or lack thereof.