Wikipedia Prankster of Fake Bio Outs Self
Link), relied on the generally positive and honest intentions of users to contribute items to its database.
The problem with anyone being able to edit entries is that malicious intentions are just as easy to do. This is exactly what happened as the popular web encyclopiedia finally succumbed to such an incident, when a prank modified an entry about John Seigenthaler Sr., founder of the First Amendment Center and chairman emeritus of The Tennessean, alleging that the man was involved in assassinations of John and Robert Kennedy.
The prankster recently admitted to the act, and the story has become a lesson about how sites should prepare for any eventuality and how, on the Internet, your worst nightmares, if not addressed early on, can indeed happen.
Although the self-policing, self-organizing nature of the site should "balance out" such occurrences, and other users would eventually correc the offending entry or change, the site is simply too popular that most entries go unchanged, even those with misleading or even altogether malicious changes.
The SeattleTimes story is here.