Disclosure: I work for the Oregon State University Open Source Lab, which recently received donations from Facebook.
I've been out to this datacenter. They employed quite a number of locals to build the place, and although the skeleton crew is only 35, they plan to keep a bigger crew of hundreds out there most of the time. In the medium term, they plan to build *two* more buildings the size of their current one, extending their current need for construction for another two years or so, and requiring a reasonably-sized group of engineers to live in the Prineville area for a while. So Facebook's put money, jobs, and consumers into Prineville, and apparently, according to the locals, this was a real lifesaver for many of the construction workers who were otherwise broke and unemployed.
I'm not a fan of Facebook, but this doesn't really seem like a horrible corporate exploitation.