You don't have to know Java to get hired, any programming language is fine. You do get asked design questions. I think making the leap from these 5 questions to "This is the #1 problem Google has and why they fail at social networks" is a bit far fetched, but it looks like I'm the only one...

The impression I got was that you don't have to know Java, but you should know at least one of Python/Java/C++. They strongly prefer the latter two.

The leap from the questions to google failing at social networks is far fetched, though.