I recently started asking in response to first contact from a recruiter. "I can't afford the time to look at positions without compensation expectations stated" seems to work pretty well. So far that's gotten hard numbers out of everyone but google, who basically says "as much as it takes".
I haven't gone through the interview process yet, but when I asked about salary last time a recruiter called, they said if I made it through the interview process they're sure they can do what it takes to come up with an offer that works. Which is basically a non-answer, but given Google's resources is fairly believable.
