I applied for a job recently with Google and experienced the most detailed interview process in a long time. It is quite tough though, I had 4 telephone interviews lasting approx 20/30mins before getting called in for a series of one to one interviews with various different managers/staff members. The personal interviews lasted approx 2hrs one evening after I had finished my current days work, during which I saw and was interviewed by 4 diferent people. I unfortunatley wasn't successful and the did offer feedback from my final interviews, always handy, however I was a bit diappointed to hear that one of the comments was that I was not "enthusiastic" enough about working for Google. I am very detailed when going for job interviews and always do backround research on the companies but after 8 interviews,the final series which were as I've already said after a normal full days work, I though using that was a bit harsh. Company knowledge is a must when interviewing with Google as you will get asked about their products and services at all stages. They seem to be a fun employer to work for. Their offices are very modern and unconventional and staff happiness seems to be quite important, at least thats the impression I got.
Good luck if you go for a job