ESRI ArcGIS Desktop 10.1: ArcMap
This is the appearance of the [Change Layout] tool, in the Layout tool bar. it'll normally be greyed out if you're in map view.
It opens a new window with two tabs. One to point to your own templates on localdisk, another to a designated network location.
If you ever need to change a layout without starting a new file and template, there is a tool called [Change Layout] under the Layouts toolbar. This will allow you to select a new template without discarding any existing datasets, styles or annotation in layout view.
I discovered this function when I wanted to resize an existing map from A3 to A1 paper size for a customer. Prior to this I would painstakingly create a new ArcMap window, then select the required template and add the relevant datasets and styles. This now means I don't have to create a whole new map if there are changes to the page size.
It might sound trivial if you are already aware of this functionality, so this is just a reminder that such a tool exists.
An important note is that by changing the paper size from A3 to A1, the map scale was different and I had to readjust the size of my text and symbology to suit the new map scale. Maybe there is another shortcut for this?