I know that my son's year (class of 2008) they seemed to take a bunch of students off the waitlist. With this year being so different (the end of EA/ED at Harvard and Princeton) I guess they really don't know how many people will come to Stanford. I did hear that they had a higher-than-expected yield last year, and so as a consequence housing is overcrowded (it always has been anyway) at least for some; I guess that might lead them not to take anyone, or very few, even if their yield is not as expected.
My daughter was rejected
and in a way it is a relief to have closure. But if she had been waitlisted, as hard is it is to still have that glimmer of hope, I'd be fine if she took a spot on the waitlist just so she didn't wonder "what if"--especially if they started taking kids off the waitlist. As long as you pretty much focus on the school that you do ultimately accept, having that slight possibility is not that bad I think.