Part of Buddhist practice includes avoiding the 10 non-virtuous actions. One of these actions is divisive speech. I think this project managers should pay attention to this one.
Divisive speech can be thought of as any words that can bring disharmony or create animosity. Politicians do this a lot; trying to create a division between themselves and their opponents while making their opponents look bad.
This type of speech can happen on a project team as well. While I feel conflict can be good, if the conflict includes divisive speech, it can hurt the team. For example, discussing the merits of .NET or Java can be a healthy discussion, but when it turns to insults, there's no benefit.
A successful project relies on a effective project team. This takes time to develop. It's the project manager's job to see that this happens. It can be as simple as having some ground rules established at the start of the project that guides the right behavior. Once the team gets rolling, these rules won't be necessary but during the forming/storming stages, they can help the team move in the right direction. What ground rules do you put in place at the start of a project to ensure your team's success?