An American hacker's program called "Wikiscanner" that traces the source of Wikipedia edits has fingered the CIA and the Vatican. The CIA was its usual evasive mode when it came to answering questions saying only "While I cannot confirm whether any changes were made from CIA computers, the agency always expects its computer systems to be used responsibly" and the Vatican closed all its doors and windows and pretended like no one was home.
Implications - But it's not just major institutions like the CIA and the Vatican that are responsible for editing their own Wikipedia pages. The profiles of former CIA Cheif Porter Goss and superceleb Oprah Winfrey were altered by people viewed as sympathetic to them. There is also rumors that a computer owned by the US Democratic Party was used to make changes to the site of major talk radio host, Rush Limbaugh.