Are Corporations (and Their Shareholders) Paying Enough Taxes?

You might have heard about the GAO study that came out yesterday which said that 23% of large U.S. corporations paid no income tax from 2001 to today.  A few thoughts on this:

• Many of these companies were paying foreign income tax on foreign operations.  It's unfair to expect a U.S. company to pay income tax to two countries on the same income.  We should adopt what the rest of the world does and move to territoriality
• According to the GAO study, the lion's share of the deductions against corporate profits were not any accounting trickery, but bread-and-butter items like wages, interest, and other ordinary and necessary business expenses.  Does anyone propose denying corporations the ability to deduct regular expenses of running their businesses?  How about the fact that wage earners, corporate bond owners, and other businesses face a concomitant tax liability on the other side of this corporate tax deduction?
• The latest CBO data shows that corporations paid $370 billion in income tax in 2007.  This doesn't count the hundreds of billions of dollars in payroll tax and excise tax.  To put that number in perspective, total tax revenues were that level back in the Carter Administration.  I think corporations (and their shareholders) are doing their part (especially when one considers the double taxation of capital gains and dividends)