Wikipedia seems to be assuming an interesting role in the global response to disaster: the web home for the best current information. In the aftermath of the December tsunami, Wikipedia slowly embraced this role; in the wake of Hurricane Katrina, the Wikipedia entry almost immediately became information central. This undoubtedly comes as a combination of both Katrina hitting an area already home to large numbers of web users and media outlets, giving more sources to draw from, and Wikipedia users recognizing the site's value during disasters.
(Hat tip to W. David Stephenson)
Also, its news counterpart - WikiNews - serves such a purpose continuously, disaster or not.
Wikipedia certainly is one of the most remarkable and comprehensive websites on the Net, though. It never ceased to amaze and amuse me.