Expect a very long interview process. I started interviewing in early october through a internal refferal. I did a phone interview with a current PM, who seemed a bit bored the entire time. He asked me questions about my resume and past projects. The design questions were pretty simple, for example "Design Google Radio." I found out about a flyout maybe 3 weeks later, then flew out in early November.
The flyout was nice, if a bit long. I had 5 interviews of the course of the day, and they told me that the sixth had been canceled. The first two were product interviews, where I would talk about what I was passionate about, and then they would suggest a product based on that. It was fairly free form, so I don't think this method of interviewing leads to re-used questions. I had basic estimation question (How much does it cost to run Youtube for a day), and then lunch.
Lunch was actually pretty bizzare, it was just talking with a Product Manager who had just graduated from the APM program. I think the point of this interview was to let me cool my heels and to see what I was like socially. He told me that less than half of his APM class was still working at Google, and seemed pretty jaded about working there. He seemed to think that the company culture had changed a lot, that politics was the only way to move up, and that getting on the right project was the only way to advance in the company.
I had a really basic technical interview after lunch, then I was told I was done for the day. About two weeks later I was later contacted and told that while I excelled in all of my interviews, I wasn't quite what they were looking for. They said that they had only postive feedback, and asked me to interview for another position.