Yes, the CIA Spied on the Senate
Earlier this year, CIA Director John Brennan accused staffers from the Senate Intelligence Committee of removing classified material from the CIA office where they were researching a report on the agency's use of torture during the Bush administration. This turned out to be very poor tradecraft on Brennan's part, since it implicitly revealed the fact that the CIA was spying on Senate staffers even though it wasn't supposed to. Brennan tried to mount a suitably aggressive counterattack to Senate outrage over this, but today it all came crashing down:
CIA employees improperly accessed computers used by the Senate Intelligence Committee to compile a report on the agency’s now defunct detention and interrogation program, an internal CIA investigation has determined.
....The statement represented an admission to charges by the panel’s chairwoman, Dianne Feinstein, D-Calif., that the CIA intruded into the computers her staff used to compile the soon-to-be released report on the agency’s use of harsh interrogation methods on suspected terrorists in secret overseas prisons during the Bush administration.
CIA Director John Brennan briefed Feinstein and the committee’s vice chairman, Saxby Chambliss, R-GA, on the CIA inspector general’s findings and apologized to them during a meeting on Capitol Hill on Tuesday, Boyd said.
I find that my reaction remains one of schadenfreude. Dianne Feinstein and the rest of the Intelligence Committee seem to be mostly unconcerned with the omnipresent surveillance apparatus constructed by the US intelligence community, so it's hard to feel very sorry for them when they learn that this apparatus is also sometimes directed at Senate staffers. If this affair had persuaded a few senators that maybe our intelligence chiefs are less than totally honest about what they do, it might have done some good. But it doesn't seem to have done that. With only a few exceptions, they're outraged when the CIA spies on them, but that's about it.