Juan Cole has the best summary of the Rep. Jane Harman scandal that I have seen:
The US is spied on, and a classified Pentagon document is passed to the Israeli embassy by AIPAC officials. They are caught because the FBI had them under surveillance. Apparently the FBI is one of the few US government institutions that is not corrupt on the issue of foreign influence on US institutions and policy. Then when the two AIPAC spies are indicted, a Mossad agent attempts to derail the prosecution by suborning a member of Congress and promising her the chairmanship of the Intelligence Committee.
Go read the whole post for the details.