I like to call this Network Aware Printing as that is what it is.
Basically what this allows you to do is to have different default printer settings based on the network you are connected to. This is a real boon for people like me who carry laptops between home and office. So now that I upgraded to Win 7 I can setup my computer to switch the default printer based on whether I am in Office or Home and it really makes life easy (take it from me).
The way to set this up is to go to the Printers and Devices screen and select one of the available printers. You will find a “Manage Default Printer” Option appear at the top bar. Clicking that brings up a second screen that allows you to do this magic.
In this screen, first choose the option to have different default printers (This is the option chosen by default). Then start doing your mapping between the network and the printer. You need to have connected to the network at least once for it to appear here and the printer needs to be installed. Once you map, click Add and the magic happens.
So now when you change networks you will see that the default printer switches. The small green tick mark () that appears next to the default printer in the previous window actually moves too. If you want to have fun, try changing between the single default printer and location aware setting and see the default printer change on the fly.. :)
Do note that this is mapping a network to a default printer. So if like me you travel to different Offices which share the same basic network, then you still may end up having the wrong default printer. I am still trying to find if I can some how get this to work based on a subnet, but have not found a way to do it yet.
Also to note this is supposedly available only on the premium versions (Professional and Ultimate) of Win 7 and only on Laptop or other mobile devices.