According to Assange, the explosive 'Wikileak' would be of the type similar to the Echelon system. For those that aren't aware of that system. It is a secret, or was a secret, program that was engaged in mass spying on the citizens of the US, Australia, New Zealand, Canadia, and Britain. Echelon involved the gathering of mass amounts of electronic information and putting in a database for analysis.
....Intelligence monitoring of people in the area covered by the AUSCANZUKUS security agreement has caused concern. Some critics claim the system is being used not only to search for terrorist plots, drug dealers' plans, and political and diplomatic intelligence but also for large-scale commercial theft, international economic espionage and invasion of privacy. British journalist Duncan Campbell and New Zealand journalist Nicky Hager asserted in the 1990s that the United States was exploiting ECHELON traffic for industrial espionage, rather than military and diplomatic purposes.....(source: wikipedia)
The excuse for the intrusive electronic spying on citizens by the government is that it is needed to keep us free. But it would seem that an intrusive spying system without a warrant or judicial review doesn't contribute to freedom but is merely an expression of fascism.
If Assange has information on the vast monitoring of people all over the world. It wouldn't be surprising. But perhaps just what the military industrial complex is monitoring might be the troubling part.