5 times now has my MacBook randomly shutdown. Luckily I was never in the middle of doing any real work -- its usually right when I boot up or wake it from sleep. But still it should never happen in the first place. I'm actually going to just deal with the issue until Apple has a known working fix for it or issues a total recall of the line.
Sean also had his book randomly shut down on him a number of times and had it fixed. Problem is he isn't sure he has the "right" fix and doesn't know if it will start happening to him again.
Dave Winer has been keeping track of other fellow mac users with this and other related issues.