Can you "disappear" a huge natural disaster with the whole world watching? This is the experiment that the government of Burma now seems to be conducting. The generals evidently have two purposes in keeping the country virtually locked down - preventing the population from being exposed to direct contact with foreign aid workers, and keeping the world from hearing too much about its own criminal non-response to the horrible aftermath of Cyclone Nargis. (The latest: Burma seized the first aid shipments, but more are on the way.)
Totalitarian states disappear things as matter of course - people, crimes, and history itself. No one knows how many died in the North Korean famine of the 1990s, though some estimates put the figure as high as 3 million. It's hard to contemplate the horror of such events precisely because so much suffering and death occurred out of sight of the world, of history.
The combination of famine with brutal government oppression a la Kim Jong Il or Stalin, however, is a slow-moving, manmade catastrophe, easier to shield from outside eyes. A natural disaster creates a sense of global urgency. Even China in the last days of the Cultural Revolution managed to mobilize itself to respond to the 1976 Tangshan earthquake, which killed at least 250,000 people (though it refused outside aid, and Qiang Qing put things in perspective by saying, "There were merely several hundred thousand deaths. So what? Denouncing Deng Xiaoping concerns 800 million people.")
The networked world makes it much harder to keep the lid on. Satellites see all. Giant natural disasters are prime material for 24-hour news operations. The constant gush of information ratchets up political pressure on nations and international organizations to act, and to strong-arm recalcitrant governments to do more. Journalists with satellite phones will sneak across borders. It's not clear this will help get more aid to millions of cyclone victims, but it can't hurt, and may make other autocrats think twice about how they respond to future disasters.