Jeffrey Cufaude makes a great point when he points out that collaboration is now de riguer for success, both at an organizational level as well at a personal level.
The problem seems to be in our mindset that we still view dealing with others as a place where we have to "win" over them. This "them" could refer to anyone outside the group, from competitors, to suppliers, to customers and even (gasp!) shareholders.
This "them" also manifests itself within organizations, between teams, between departments, between business units, branches.
Primarily, this is driven by a feeling of shortage ("there's only so much budget we have, our group has to get the maximum", or "there are only so many customers for this product, we have to get them before our competitor").
The key for a facilitator, within or without, working with teams with such an attitude is to try to expand their horizons, to redefine what is the "product, the business, the community" that they are serving. The manager and facilitator has to battle entrenched mindsets and can often be a self-defeating exercise.
But the good thing is, when it succeeds, those few times can often be the moments that working seems to be the pleasure it is meant to be, one transcends the barriers of the mundane and goes back feeling "today we made a difference."