A well-written article there at avault. "I knew it all along" - succinct indeed. Having some in-depth knowledge of developmental psychology (M.S. in Experimental Psych, among other things), all I can say is "duh". Heh.
Children are very impressionable - the younger they are the more impressionable they are (think learning how to speak a language). They learn by example, and the strongest examples come from the parent(s) and family and then friends and so on. Long-term exposure to graphic violence, real or fantasy (e.g., tv, games, etc.), will undoubtedly have an effect on the developing child. What effect, the extent of that effect, etc. is still rather unknown and likely differs from individual to individual.
Our society needs to stop attributing blame to others for our own mistakes in raising our children (not a parent yet myself, but someday). It's just so much easier to blame the "media" or the "games" or the "music" than it is to own up to the awesome responsibility that is raising a child.
Might have to find me a copy of that report....