On Twitter, Sifting Through Falsehoods in Critical Times - NYTimes.com:
Deliberate falsehoods, including images showing the Statue of Liberty engulfed in ominous clouds and sharks swimming through waterlogged suburban neighborhoods quickly spread through the service, as did word that power would be shut off for the entire city of New York and that the floor of the New York Stock Exchange had been flooded.
Twitter says it cannot possibly regulate the millions of messages on its service, and that a bit of misinformation and mischief is to be expected. But in recent years, the service has become an indispensable funnel of information in critical times for many people, especially for those who lose access to power or cable TV. For them, it can be a crucial lifeline.