The Center on Budget and Policy Priorities has released Misconceptions and Realities About Who Pays Taxes:

A recent finding by Congress’ Joint Committee on Taxation that 51% of households owed no federal income tax in 2009 is being used to advance the argument that low- and moderate-income families do not pay sufficient taxes. Apart from the fact that most of those who make this argument also call for maintaining or increasing all of the tax cuts of recent years for people at the top of the income scale, the 51% figure, its significance, and its policy implications are widely misunderstood.

Oft-Cited 51% Figure Is Temporary Spike Caused by Recession

  

Lower-Income People Pay Considerable Payroll, State, and Local Taxes