It's not unusual. In the Bible, Jews were advisers to lots of gentile leaders, starting with Joseph advising the Egyptian Pharaohs on how to avoid their seven years of famine. Later, you have Daniel advising Persian King Darius, ironic in light of today's Israel/Iran tensions. My only question is whether Jews are more loyal to the countries where they live or to Israel. The only example I can think of in the Bible is Nehemiah, the king's cup bearer, who persuades the king to let him rebuild the wall around Jerusalem.
We have not had a Jewish President. It would be interesting to know whether Al Gore's picking Joe Lieberman to be his vice president helped or hurt his campaign. Certainly it looked odd for Lieberman to support John McCain in the last election. Some new book says that Henry Kissinger is responsible for America surviving the Watergate scandal. Kissinger certainly spent a lot of time working on Israeli issues, but, perhaps mistakenly, I think he was pretty even handed. I think he was committed to Israel's existence, but was willing to press Israel to make concessions to the rest of the world. Although Barak Obama is certainly not Jewish, he is surrounded by a lot of Jewish advisers, starting with Rahm Emanuel and Larry Summers, whom I find suspect. For some reason I have no qualms about Paul Volker or Ben Bernanke, who for some reason I consider totally American, even more trustworthy than Kissinger.