See Who's Editing Wikipedia - Diebold, the CIA, a Campaign

Diebold Editing Wikipedia: "On November 17th, 2005, an anonymous Wikipedia user deleted 15 paragraphs from an article on e-voting machine-vendor Diebold, excising an entire section critical of the company's machines. While anonymous, such changes typically leave behind digital fingerprints offering hints about the contributor, such as the location of the computer used to make the edits. "