There was an article in the NY Times a while ago about how Google was shifting from their "ask crazy CS questions and post puzzles on billboards" interview process to a more standardizable "algorithmic" one. I'm guessing stories like this about being asked a standard set of questions of questionable relevance are the fallout from that transition.
As I'd heard it, the algorithmic piece would only be used in the case where they would have normally (with the crazy questions process) passed over the candidate.
One of the pieces of culture at Google is that everyone wants to make sure everyone there is smart, so they basically send away anyone they have doubts about, even if the person's actually genius-level. The test would be a way to, without subjectivity, indicate some cultural fit that the interviewer by bad luck missed.
See it this way, Google rejected you and in doing so, its allowing you to grow and who knows you may start something and become its competitor :)
This is what i say when i get booted out in interviews :D
