This recent podcast from Planet Money goes into some depth in examining the security measures that exist to ensure the integrity of the jobs figures and prevent them from being released early. I would imagine that any monkeying with the data would be trackable (and tracked):

http://www.npr.org/blogs/money/2012/...he-u-s-economy

lhamo

(This is linked in in the snippet redfox posted above, but thought worth pointing out separately).