From Planet Money's blog, http://www.npr.org/blogs/money/2011/07/27/138738198/3-reason...
The full podcast, "Would a downgrade matter?", is an excellent listen: http://www.npr.org/blogs/money/2011/07/28/138721364/the-tues...
The whole point of a rating agency is to provide you with research that you couldn't get based on your available resources. But every economist in the world is a resource on the U.S. Government's viability. You can turn on CNBC and get 24 hour coverage of it.
So the U.S. is a special case and the ratings agencies don't mean all that much in regards to it.
While that may have been true a couple of years or may be even months ago, I'd say that this is anything but certain. There are a lot of people and government through out the world who would like to see the U.S. weakened.
On Monday you can short every major company the downfall will be significant. This will be very interesting to watch the next world recession is on our doorsteps.
Money does not care who you are or what you do.
That's the problem. No one else knows either. Monday is not going to be a good day.