As I read in the LA Times, researchers have proven that in people involved in a financial transaction, inhalation of oxytocin significantly increases their willingness to trust a complete stranger with no proven track record.
Oxytocin is a hormone which is normally produced in people, and is known to help induce contractions during labor and milk production in the breast. This is a further example of the role this hormone likely plays in other aspects of our biology.
The researchers are careful to point out that while this knowledge could be used for nefarious purposes, the required dosages to achieve any significant effect would require a very visible mist in the air. The hormone has to be inhaled – otherwise it degrades too quickly to have any effect (no pills).