Well ain't something. In Windows Explorer, hold down the Shift key and right-click a folder. The context menu now gets a few extra options: Open Command Window Here and Copy As Path.
The first one does what one of my favourite XP Power Toys did, which is to open a command prompt at that location. This will probably go joyfully astray if you try opening the command prompt on a network folder (Powershell can do that for you).
The second one is something Really Useful. When i want to send a mail to a colleague about a file on the server, i can copy the full UNC path name to said file. The previous alternative would have been to surf to the containing folder, copy the file name from the address bar, then select the file, press F2 to enter Rename File mode, select ^All of the file name (Windows 7 and Server 2008 will select all but the file extension, which usually is a Good Thing), ^Copy the file name, and paste that into the mail i was sending.
This is what is known as Good Laziness.
Thanks to Petri.