I knew someone who had graduated a few years before me from my university and was talking to him about his position with Google. Eventually he helped refer me to HR after I filled out the online application. I waited about 2 weeks and got the initial email inviting me to a phone interview. The format was two 30-minute interviews with 2 different people. I was VERY nervous and ended up not doing too well and did not get called back for that position. They asked me the usual "Why Google? Why Sales?" questions and general behavioral questions about working on a team or having a difficult client. They also asked me about AdWords, its advantages, and how I would describe it to a child.
What tripped me up were the questions about Google products. They asked me to discuss my favorite one and describe how I would market it to someone. They also asked about a product that currently is not using the most effective marketing strategy and how I would change that.
Luckily, my friend also referred me to a couple other positions so after another couple weeks I got a call from an HR representative asking me about what I might be interested in and the teams that were still interested in me. Later on that week I got my second chance at a phone interview for this new team. They asked me very similar questions so this time I was prepared. Some new questions I got were, "If you were given $10 million, what would you do with it?" And, "If you were given $10 and told to do something useful with it, what would you do?" They also asked me to describe something that I knew a lot about that the interviewer likely wouldn't know.
Later that day I was invited for an on-site interview. They paid for all my expenses and everyone at the office was extremely nice. The format once again was two 1-on-1 interviews. Most of the questions I got on-site were similar to what I'd gotten during my phone interviews.
Overall, no one is trying to trip you up like you often experience in other places so it can be an easy interview if you spend some time preparing. Make sure to know AdWords and find a way to show your personality!
It took 3 weeks after my on-site to get an offer which is a little longer than usual, but whenever there was a delay I'd get a call from HR so it helped me not worry too much.
