What is a wiki/Talk

Isn't this a non-secure means of documentation?

Depends on what you mean by non-secure. You've got to be more specific --Robert Merkel

Couldn't I erase everything in the Wiki network if I was a terrorist?

Only if you steal the backup tapes at Bomis, who host the Wikipedia, and hunt down the tarballs of Wikipedia data that are publically downloadable from the site. --Robert Merkel

How is Wiki text replicated in case of such an attack?

See the above answer. Anybody can download the Wikipedia data tarball. However, public knowledge that certain individuals or groups are doing so would be helpful in maintaining confidence in the public accessibility of Wikipedia. It'd also be good if people also do so covertly in case of some unforseeable legal threat. --Robert Merkel