Generally datacenters are weary of photos due to housing hundreds or thousands of different customers, many of which who do not want photographs taken of their equipment or even to have the geographic location of their equipment exposed (governments, financial institutes, etc). At Facebooks datacenter the only occupant is Facebook, so it's nice that they aren't as paranoid and will show these photos.

Well, except the "no photos of the older equipment" rule that Scoble apparently ran into :-)