while replacing my RadMenu for the new RadNavigation, I was forced to stop because the RadNavigation does not support columns like the RadMenu can e.g.

<telerik:RadMenu runat="server" ID="radMainMenu" MaxDataBindDepth="2" EnableRoundedCorners="true" EnableShadows="true" EnableTextHTMLEncoding="true">
<DefaultGroupSettings RepeatColumns="2" RepeatDirection="Vertical" />
 </telerik:RadMenu>

Keep up the good work,
Thanks.