The PanelBar is a standard ItemsControl and it is quite similar to the TreeView. The content of its children is not restricted to string, but as the property suggests (object), it can be anything.
ItemTemplates, TemplateSelectors, Styles & StyleSelectors work as well.
It seems we have overlooked changing the Silverlight to WPF in the PanelBar's documentation but the API and behaviour of the control is the same. Thank you for pointing this out. We will surely fix it.
The reason why we implemented different functionalities is that there are differencies between the WPF and Silverlight platforms that we could not overcome. For example, the WPF base ItemsControl comes with functionality like grouping and LayoutTransformations which are not available in the Silverlight framework.
We will be happy to help you if you face any other difficulties or have further questions.
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.