Digital information by it's nature is changeable. Flip a bit and suddenly Tuesday's Wednesday. If you can convince everyone (using, I dunno, shiny iPhones, Crackberries, laptops, etc) to store their knowledge and identity digitally, you can effectively control history, and therefore people and the future, just as completely as Orwell's "memory hole".
Information storage is designed to be malleable, and the networks knowledge flows across is designed to be completely trackable.
Any "hacker" who thinks they know better doesn't understand the nature of digital data and networks, or the spirit DARPA created them in.
Taken 12/10/09 in Shreveport, LA...shows clearly both kinds of "trails" left behind by aircraft over our heads every day. I ask you - how on earth can these two trails BOTH be water vapor condensation?