A new study seems to show that there is no relationship between violent videogames and real-life aggression. From ScienceDaily:
Writing May 14 in the International Journal of Liability and Scientific
Enquiry, Patrick Kierkegaard of the University of Essex, England,
suggests that there is scant scientific evidence that video games are
anything but harmless and that they do not lead to real world
aggression. Moreover, his research shows that previous work is biased
towards the opposite conclusion.