About 1 week after uploading my CV on the dropbox website, I received an email to ask whether I was available for a first phone call screening. The call lasted about 30 minutes and the interviewer asked very basic questions (why do you want to work at dropbox, tell me a little bit about yourself, explain cloud computing to your grandmother). In the end, the interviewer asked if I would be available to go to Dublin the following week. I got an email about a week after with interview dates in Dublin (and If you're not from Dublin, Dropbox will pay for your flights, stay and reimburse your expenses for food and transportation).
They will schedule two rounds of interviews: the first round lasts about 2 hours and if they like you, they call you back for the second one-hour round the following day.
During the first round, I met four dropboxers. Each interview lasted about 30 minutes. The first question is the usual 'tell me about yourself'. All other questions were mostly related to the motivation to work for dropbox, which role you're interested in, how do you imagine your ideal day in dropbox, the tech world in general, some guess estimates.
i wasn't called back for the second day. Even though I didn't get the job, it was a positive experience.