Grades and where you went to school doesn't matter.

[AkaiOkami]

I cannot speak for the whole company but, having been a temp for Google's HWOPS (the department that does server maintenance), it uses degrees and knowledge of linux to move up the hierarchy. The entry level position is assembler (server hardware maintenance). With a degree in anything, a person can move up to engineer(server software maintenance). With a degree in anything, a certificate in linux, and experience working with linux, a person can then move up to engineer II. After engineer II, a person has to start empire building by building connections with management to continue moving further up the hierarchy ladder.

PhD in computer science, in the eyes of tech industry is not what you think. These are mutli-billion dollar companies(Apple came close to becoming the world's first trillion dollar company) that hire PhDs just so that the competition can not get their hands on them. They hire these people, put them behind a desk and then let them go to waste, and every now and then give them a project to keep them from getting bored. They do this because it is cheaper to hire them, and keep them occupied then to let them create a new product that the competition can use to get a head. Hiring also, prevents them from creating a new app that could be the next facebook, candycrush, etc, on their own. Thus, hiring PhDs prevents competition.