I work down the street from their menlo park/willow road campus. Right now Facebook is building an apartment complex across the street from HQ. They've promised to only rent 10% of the apartments to their employees with the other 90% being offered to the general public at market rate.
Despite the nice sounding name, Menlo Park's east side is akin to East Palo Alto. Slum neighborhoods, crime, ghetto. With the influx of google/facebook employees however the neighborhood is slowly gentrifying.
I think facebook wants to turn the neighborhood into something more appealing for their employees.