You can define two types of RadTreeView templates: 

1.   Global Template - template that is automatically applied to all tree-nodes

2.  Per node template - template that overrides the global template on a node basis.

This example shows the usage of per node templates:

<radT:RadTreeView

    ........

    <radt:RadTreeNode Text="Inbox">

        <NodeTemplate>

            ...

      </NodeTemplate>

    </radt:RadTreeNode>      

    ........

</radT:RadTreeView>