Googler here -- I have no idea what happens to people who pass the challenge, but it's been widely reported that Google is in a hiring slowdown right now. So I would expect the response rate from Google to be lower now than 6 months ago, and probably lower than it will be in 6 months.
Is this a seasonal thing? Or does Google hire people in batches? If not, together with joseph_c's answer this suggests the odds are a worse than I thought.
In years since past, the foobar challenge first appeared. 5 levels of ever harder coding challenges, and if you bested the first three you'd be given the option of providing your details to Google. There was a decent chance you'd be sent an interview request sometime later or , if you applied to them yourself, you're application would be given extra weight. Recently, I got the challenge from Google and after getting to the last problem of level three, I wondered "do they even hire people using this thing anymore"? Some quick searches on medium blogs, quora and hackernews later, I was left with the impression that they don't but no one could cite a source for this.
So does anyone have any info, definitive or otherwise, that would tell me and other lost souls whether Google still hires using this thing?
Edit: changed the name