I went back to campus the other day to check my mail (I had, with an extreme lack of foresight, instructed people to send me packages there) and I walked across Wilbur field. It was awesome. The field, on top of a newly-created underground parking structure, replaces the old Wilbur field that none of us ever got to see or use.
I had been anticipating the completion of this project the entire year--not only was I excited to have a field outside of my dorm (of course, I don't live there anymore) but the project seemed to be an extremely efficient use of space. Both field space and parking are needed in that area, especially with the construction of the Munger residences, and this allows for both of them to be there at once.
I heard at some point that the underground structure cost 3x as much as a similar above-ground structure, but unfortunately I can't find the source to back that claim up. But I did find some cool information about the project. I saw a PowerPoint Presentation entitled, "The Green Roof on Stanford: Parking Structure Six"--google 'stanford parking structure six green' and it will be your first entry--that describes how the roof works. There are a number of
elaborate drain systems to ensure that the garage doesn't flood if it rains/when the sprinklers turn on (which, as we all know, happens about every three minutes). The entire field is also slightly sloped to also help drainage and support.
You can also see a bunch of pictures of the project at http://mungerhousing.stanford.edu/gallery_new.html. If I had a car on campus, I would totally park it there.