I'd say Joel Spolsky is somewhat unique in this, although Google has had bias for C++ in the past [1]. Spolsky has long been an advocate for expecting developers to be competent in C [2].
FWIW, Google generally expect engineers to know bit manipulation. Certainly I was asked some, I don't know if everyone necessarily is but I wouldn't be surprised if they were.
[1] http://www.cforcoding.com/2010/07/my-google-interview.html
[2] http://scott.yang.id.au/2008/04/joel-spolsky-and-jeff-atwood...