...found [link|http://usembassy.state.gov/posts/ks1/wwwfds82.pdf|here]. Page 4. Under "Acts and Conditions":
[...]accepted or performed the duties of any office, post, or employment under the government of a foreign state[...]
I apparently will have to sit corrected in that it automatically disqualifies you from receiving a US passport. But you must declare that you have done so, and explain what you did.