Stacie,
I am sure what others will have already hit this point, but having a common goal is what I have seen support knowledge sharing the most. When the team realizes it has to rely on each other to get the mission accomplished, knowledge sharing occurs. I saw this daily when I was in the military. I don't see this as much in the defense industry, but when knowledge sharing occurs, it's because the team has a common goal.
Regards,
Cindy