I wonder if the next thing Yahoo! does is build a huge office complex. That's the thing big silicon valley companies do before they die, although Yahoo! should have done it in 2005-2007 on this timeline.
It was being discussed in 2009; http://www.businessinsider.com/yahoos-humongous-new-hq-see-i... Not sure if there's any recent news on it though. It's pretty close to the new "SF" 49'ers stadium so it was probably a good real estate move on that front.