In short, rating agency may reconsider the AAA rating of the US government.  Suprise?  no.  Implications?  Hardly any, according to Felix Salmon, a long-time blogger currently blogging in Reuters.

 "The most important thing to remember here, however, is that ratings agencies don’t matter any more. They lost their credibility when structured finance blew up, and the number of people buying Treasuries because S&P says that they’re triple-A rated is exactly zero.

There are lots of triple-A rated securities; people buy Treasuries because they’re liquid. The US triple-A may or may not disappear at some point, but if and when that happens it’ll be a lagging indicator, and there will already be a select group of alternative securities which are trading at lower yields in dollars. So long as Treasuries have the lowest yields in the dollar-denominated world, they will retain their triple-A, and there are much more important things to worry about."  

Related post from Bloomberg can also be read here.