Pretty interesting stuff,
I looked up propranolol and it's mainly used to treat hypertension. According to wikipedia it's also used by people with stage fright. Anyway, after checking up on the research there seems to be studies concerning post-traumatic stress as well:
(Pilot study of secondary prevention of posttraumatic stress disorder with propranolol) http://www.sciencedirect.com/science/article/pii/S0006322301012793 (cited by 658)
(Immediate treatment with propranolol decreases posttraumatic stress disorder two months after trauma) http://www.sciencedirect.com/science/article/pii/S0006322303004128 (cited by 356)
Some study about propranolol and its effect on people's ability to detect sadness:
(Administration of the beta-adrenoceptor blocker propranolol impairs the processing of facial expressions of sadness) http://link.springer.com/article/10.1007/s002130000654 (cited by 60)
Then there was some study about psychopathy where propranolol was mentioned but it was mainly about the neurology behind psychopathy and the connection between psychopathy and amygdala:
(Neurobiological basis of psychopathy) http://bjp.rcpsych.org/content/182/1/5.short (cited by 349)
"Certainly, administration of the β-adrenergic blocker propranolol, as well as amygdala damage, blocks the improvement in episodic memory for emotionally arousing events, as well as disrupting the processing of sad facial expressions ( Harmer et al, 2001)." (harmer is the previous article)