Would administering oxytocin in games of deception improve performance?
One of the very recently published studies linked to in the question, on the relationship between exogenous oxytocin administration and ability to accurately detect deception, instructed participants to self-administer oxytocin by nasal injection before evaluating contestants' decisions in videos of the Friend or Foe game show (Israel, Hart and Winter 2014). They reported that:


  Rather than improving subjects’ inferences about others’ mental states, oxytocin impeded accurate assessments of trustworthiness in risky social exchanges. Oxytocin decreased prediction accuracy but did not increase predictions of cooperative behavior in general.


The evidence reported in Israel, Hart and Winter (2014) clearly implies that exogenous oxytocin would have deleterious effects in games of deception such as poker. However, it may not be as simple as that. 

Another study proposed that oxytocin may exert its apparent effects by increasing the attentional salience of social information, and that the effect may thus be mediated by interpersonal factors like perceived group membership (Ten Velden et al., 2014). They reported a complex set of results broadly consistent with this hypothesis based on a simplified poker game task:


  Results permit three conclusions. First, intranasal oxytocin does not increase indiscriminate benevolence in humans. This conclusion follows from the observation that in competitive interactions, humans given oxytocin reduce competitive approach only when their protagonist is an in-group member, and do not show an increased preference for settlement when protagonists are from a rivaling out-group. Second, and relatedly, intranasal oxytocin promotes cooperative conflict resolution in within but not between group competitions. This conclusion follows from the observation that, compared to placebo, oxytocin increased a preference for settlement with in-group protagonists, but not with out-group protagonists. Third, and finally, in competitive interactions, intranasal oxytocin does not influence preferences for withdrawal. This conclusion follows from the observation that regardless of competitive strength, and regardless of the protagonist's group membership, oxytocin exerted no influence whatsoever on the tendency to “fold” in the competitive poker-game studied here.


Note that while the Ten Velden (2014) study used a poker-like task, it did not report on differences in ability to detect deception. 

References


Israel, S., Hart, E., &amp; Winter, E. (2014). Oxytocin Decreases Accuracy in the Perception of Social Deception. Psychological science, 25(1), 293-295.
Ten Velden, F. S., Baas, M., Shalvi, S., Kret, M. E., &amp; De Dreu, C. K. (2014). Oxytocin differentially modulates compromise and competitive approach but not withdrawal to antagonists from own vs. rivaling other groups. Brain research, 1580, 172-179.