Sorry, I just picked the first result on Google. I learned this tidbit from a previous posting on HN; apparently the CIA (or NSA?) recruits heavily from Brigham Young University.
There is the possibility that they trend towards Mormons due to some belief/statistic that they are more likely to respect authority, or unquestioningly follow orders.
On the other hand, Mormons do a lot of missionary work where they learn the local language, in addition to customs, etc. This is also something extremely valuable to intelligence organizations.
There's a reserve/guard unit (can't remember which) in Utah that is comprised largely of Mormons who became linguists for the Army. Supposedly, it's the most talented and diverse group of linguists ever assembled, and they have people who speak languages that no other person in the Western world knows.