I applied online and a recruiter contacted me about a week later to schedule a phone interview. Though the phone interview was seemingly "standard," it was a little more in-depth than most, so be prepared to answer somewhat penetrating and specific questions about your resume. Be ready to defend or explain in very clear examples anything you've put on your resume, all the way back to college (no matter how far removed you are from college).
Phone interview went well so at the end the recruiter said I'd be hearing from a coordinator to schedule a time to go in and take a logic exam. Logic exam was by no means easy, but wasn't insanely hard either. But it did involve common sense and, gasp, logical reasoning. I liked this because it showed that even though this is "just" for an admin position, Google still wants incredibly smart and talented people working in every corner of the company. Being an admin may not be rocket science, but you'd be surprised how many people can screw it up. Clearly Google wants to avoid those people.
Logic exam contained questions like you'd find on an LSAT/GRE. 2 reasoning problem sets and a 3rd open ended "essay" (I use the term essay loosely).
After that, recruiter called to schedule 1:1 interview for me. Under normal circumstances I think they would have flown me out to Mountain View, but since I was living in NYC, they had me go into NYC office and interview over videoconference with person in Mountain View. The next day I found out that position went to an internal candidate, but they still flew me out to Mountain View 2weeks later for a day of three 1:1 back to back interviews for 2 (same) open positions.
Interviews were 30 mins each with little to no time in between. Largely experiential and personality-based, asking me to give concrete examples of various work experiences I've had before. Though not intimidating or "tough," they don't let fluff answers just slide by and will certainly ask you a question again if they felt like you didn't give a substantive answer.