It's too bad people have had a hard time getting these, they look really cool and I love the project's idea. Really looking forward to getting one myself.
There was a lot of experimental psychology research in the last fifteen years or so in this field. It generally concluded that exposure increased some measured antisocial behaviors and decreased some prosocial behaviors, but whether that translates into actual aggression against others is unclear.
A longitudinal study following about 1500 children for three years was recently published that claims "sustained violent video game play was significantly related to steeper increases in adolescents' trajectory of aggressive behavior over time."[1] Again, whether this translates into real world violence is unclear.
[1]Willoughby, T., Adachi, P. C., & Good, M. (2012). A longitudinal study of the association between violent video game play and aggression among adolescents. Developmental Psychology, 48(4), 1044-1057. doi:10.1037/a0026046