According to this chart, debt is set to exceed U.S. GDP in 2012.
For some other scary projections see this recent working paper by The Bank For International Settlements titled The future of public debt: prospects and implications. For example, the authors project that for the U.S. to get to pre-2007 crisis level's of debt within 5 years, we would need to run a SURPLUS of between 8-12% of GDP. Another projection shows that the interest on the debt will hit over 25% of GDP by 2040 - that's not 25% of the budget - that's 25% of the nation's economic output just to cover interest on the debt.
Even under their ideal scenarios of growth, the levels of debt and debt service relative to various nation's GDP are enormous and explode going forward.