Yes. There are special tax regulations for expats, but if otherwise required to file based on income, you still need to both file and pay your US federal taxes. Expats do receive an automatic time extension for the date to file; however this extension does not apply to paying any taxes due.
The IRS provides this tax guide (Publication 54 (2005), Tax Guide for U.S. Citizens and Resident Aliens Abroad) for overseas Americans:
http://www.irs.gov/publications/p54/index.html
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