The recruiter wanted to know a lot about my academic credentials. Once I related a particularly high standardized test score, there was more interest and an invitation they'd like to phone screen me. The recruiter provided a set of documents suggesting things I should be familiar with with emphasis on Google Labs.
The phone screen involved several open-ended questions. None was particularly difficult. A week later, the recruiter got back to me saying they wanted to have me out for an in person interview. I hadn't heard anything for three weeks, then all of a sudden a bunch of calls, "can you schedule to be out here [in three days]", "fill out all of these forms," and so on.
The in-person interviews included several sessions of "how would you?" questions and a "no feedback" lunch in the Google cafeteria.
Overall, I very much enjoyed interviewers who engaged in back-and-forth discussion -- *like there would be in real life* -- I would love to work with these people. Two of my interviewers were playing the "you haven't read my mind, try again" game and, unfortunately, they cast votes in whether we'd move forward.