The company I work for recently adopted a NetFlix style "we don't track vacation" policy. It's been about nine months, and anecdotes (no data available - we don't track!) suggest total vacation time taken is less than half of last year. I suppose that whether that's good or bad is pretty subjective.
Looking at job descriptions with their little 3.5 weeks of vacation is just a bummer now. Who wants to sit around thinking about the optimal way to use that time? Just do a kick-ass job and take vacations when you want. This benefit means more to me than a considerable increase in salary would.