Assuming you mean two-way binding (model-to-view and view to model) on the input element and one-way binding (model-to-view) on the span element, then the following view will do what you describe.
<div id="user-view"> <span>{ user:name }</span> <input rv-value="user:name"> </div>
Here is a fiddle that demonstrates action in action. It includes the Backbone adapter on the interface : and shows how to bind the model to the view (this is just a simpler example of what is already shown on the main page).
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