Twitter and Facebook have emerged as valuable tools in tracking stories where access is tough; consider the unrest in Iran and terrorist attacks in Bombay as recent examples.

But as news of Michael Jackson's death unfolded Thursday, these online tools offered ways to track the exploding story closer than the continuous coverage offered by cable TV news and more conventional outlets.

The race started when Jackson was taken to the hospital, said to be in cardiac arrest, which is fatal unless treated immediately, but no one had many details on his condition -- at least, until the entertainment Web site TMZ posted an entry at 5:20 p.m. Eastern time stating that Jackson was dead.

It was a declaration the Los Angeles Times wouldn't confirm for nearly an hour, forcing cable TV outlets and news Web sites to cite TMZ's reporting. Accounts that Jackson wasn't even declared dead until 5:26 p.m. leave lots of questions about how TMZ got its info. ("Everything starts with a tip," TMZ managing editor Harvey Levin told the Associated Press Thursday.)

The news raced across the microblogging service Twitter, making subjects such as RIP MJ and #michaeljackson among the most popular topics. A half hour before the Los Angeles Times would confirm Jackson's death, radio personality Ryan Seacrest tweeted "I am hearing from a source at ucla medical center, michael jackson has died. I am checking other sources right now."

Given the visibility of celebrities on Twitter, it makes sense that so many would express their condolences online. Even as cable TV channels scrambled to find big names for their shows, Paris Hilton told her followers on Twitter  "  :( I can't believe Michael is gone." Meghan McCain, daughter of Sen. John McCain, noted "It just feels like the end of an era for so many reasons." And MC Hammer said "I will be mourning my friend, brother, mentor and inspiration."

As a prank rumor began to spread that actor Jeff Goldblum might have died in New Zealand, a tweet from actor Kevin Spacey, who had spoken with Goldblum's manager, knocked that down (even CBS News passed along the message to its followers).

According to the Los Angeles Times, the explosion of interest doubled Twitter's update frequency and tripled Facebook's activity, as friends traded lists of favorite Jackson songs, links to treasured videos and commiserated on the unfolding media circus.

 By the time the big TV networks could offer prime time retrospectives Thursday night, fans with Twitter feeds and Facebook accounts had already seen loads of quotes, lists and video clips, traded and retweeted by a growing community of users who reacted more intensely than when Iran erupted after its recent elections and swine flu spread across the world.

"Already been asked several times if I'm 'disappointed' in Twitter for going much crazier over MJ than Iran election or Swineflu," tweeted Laura Fitton, author of the book Twitter for Dummies. "But see, Twitter's about 'What do we have in common.'  500 million have just Thriller in common, let alone the rest of his life/career."     

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