Found the chart I had posted once before somewhere:
The Tax Foundation - Summary of Latest Federal Individual Income Tax Data
Essentially, in 2010, the top 1% of income earners (those making over ~354K) pay ~38% of all income taxes collected (based on the total number of tax returns filed and adjusted gross income). The top 5% (those making over ~169K) pay ~58% of all income taxes.
From the same site:
"•The largest corporations pay the lion’s share of taxes. In 2008, the 1,937 largest companies were responsible for 68 percent of corporate tax revenue
•The overall effective corporate income tax rate on the worldwide income of U.S. corporations is between 32.1 and 33 percent, which is close to the statutory rate of 35 percent."