"SmartNavigation" is a boolean property which can be set in the page's code behind or in the @page directive... This property is really helpful in case you want to enhance user experience... Set this property to true and you will get following advantages in navigation if your browser is IE 5.5 and above...
1.) Maintaining the scroll bar position (useful in long length pages)
2.) Set focus to the same control on which it was before navigation (useful in pages with lots of controls)
3.) saving last page state in the browser history (useful when a page does not changes considerably across frequent postbacks... eg chaning control values on change of dates in calendar control)
4.) The flash effect caused during navigation (useful when your page is pretty heavy to load)