This article from the Wall Street Journal looks at changes in Google's hiring practices.
http://online.wsj.com/public/article/SB116156296729900433-BRo1QX346onSLhm2WoMYj834Shs_20061122.html

Title: Google Adjusts Hiring Process As Needs Grow

From the article:
"Now Google is attempting to fine tune its approach toward hiring staff. In addition to making the experience less grueling for would-be employees, it hopes to do a better job of offering the right jobs to the right people as it continues its rapid expansion...One initiative Google has already undertaken is reducing the number of interviews. Mr. Bock says each candidate offered a job by Google went through 5.1 in-person interviews on average in June, down from 6.2 at the beginning of the year. (A veteran tech recruiter says five to eight interviews is probably about average for Silicon Valley.) Google is also considering requiring staff members who interview candidates to submit their assessments within a week of the interview; right now, there's no strict deadline."