One phone interview, about 45 minutes. My recruiting contact sent me preparatory materials and explained the process beforehand. Interviewer opened by asking about a project on my resume; rest of the time was on a couple technical problems. I wrote code in a shared Google Doc while talking on the phone. Questions required writing algorithms involving bit manipulation. Google flew me to Mountain View for on-site interviews after I passed the phone screen. Four one-on-one on-site interviews, each ~45 minutes. Coding was done on a whiteboard. Three interviews were primarily on algorithms/data structures; the other involved OOP. Each interviewer had his/her own style, but overall atmosphere was informal and collaborative. Interviews were back-to-back. After the first two, a different employee accompanied me for lunch and to answer my questions.