Barriers

I just wanted to try and get some feedback about the barriers to implementing a knowledge management system at the workplace. We've talked so much about how important trust is for the upkeep and integrity of a wiki system, we've also discussed how employees resistance to change may affect the implementation of such systems. I wanted to know aside from these two, what other barriers may exist?

Some videos

I found these videos on youtube. They talk about some new advancements in collaborative software's.

http://www.youtube.com/watch?v=t7uFs8SbJww
http://www.youtube.com/watch?v=ssjvh6BhZL8