Sam Pizzigati has an interesting article over at Alternet that shows how little the Top 400 actually pay in taxes as a percentage of their income. It's about half of what the government should collect, 18% rather than 35% (the supposed tax rate for the top bracket):
"In 2008, the IRS revealed last week, 400 Americans reported at least $110 million in income on their federal tax returns. These 400, in a year that ended with millions of Americans out of work and home, averaged $270.5 million each, the second-highest U.S. top 400 average income on record."