Palantir is definitely a fairly well-known (if somewhat secretive) company in Silicon Valley. While Silicon Valley firms actually tend to have a reputation for being skeptical of partnering up with the intelligence community, Palantir has always focused on trying to work directly with the intelligence community, quite successfully. Palantir got a bit of notoriety a couple years ago, when it was revealed to be associated with HBGary Federal when Anonymous leaked plans to try to discredit Wikileaks and various critics (including Glenn Greenwald) in a pitch to Bank of America and the US Chamber of Commerce.