To add to that: generally, personal income is not double taxed either in this respect. Anything one hears to the contrary is usually political FUD.
Quote below from IRS. Heck, they even point out how to give them the least of your money. http://www.irs.gov/Individuals...
If you paid or accrued foreign taxes to a foreign country on foreign source income and are subject to U.S. tax on the same income, you may be able to take either a credit or an itemized deduction for those taxes.
Taken as a deduction, foreign income taxes reduce your U.S. taxable income.
Taken as a credit, foreign income taxes reduce your U.S. tax liability. In most cases, it is to your advantage to take foreign income taxes as a tax credit.