The process took 2 weeks. I interviewed at HubSpot (Boston, MA) in Sept 2010
Interview
Phone interview was pretty straightforward, they just had some basic programming and OOP questions. In person interview was much more difficult. It lasted about 5 hours in total and I met with about 10 people. By the end of the whole process, I could not even think straight, I was so mentally exhausted.
Interview questions [1]
Question 1
Given a building with 100 floors and 2 glass balls, how can you most efficiently find the maximum floor from which when dropped, the glass balls will not break.