You can toggle viewing modes in published content by using the Change view mode button in published Presenter '09 content. Here's how:
Launch the published content in a browser
Click on the Change view mode button located in the lower right-hand side of the player until the viewing mode of choice has been found
The three modes available are Standard view, No sidebar view, and Slide only view. If the Change view mode button is not available, then the content author must enable it by using the method discussed here.