I've heard Google doesn't assign new hires to a team right away, so the hiring process might just be a big talent search, where teams then interview newly acquired talent for a position on their team, after they are in-house.
One thing I'd like to remind everyone about is that I'm writing about a time long gone. Trying to guess what Google today does based on what Google did 5-6 years ago brings to mind the adage: "Past performance is no guarantee of future results."