Check out the chart showing the recent spikes in the US 10-year credit default swap. In other words, the market is now pricing-in the genuine possibility that the US will struggle to pay-back some of its long-term T-bills.

That possibility is still deemed to be quite low. But the ultimate financial question - until recently, unthinkable - is now being asked. Yes siree, the mighty US government could default. That’s how much the world has changed.

http://www.telegraph.co.uk/money/main.jhtml?xml=/money/2008/09/21/ccliam121.xml