WSUS Smart Approve is a tool for Microsoft Windows Server Update Service. Its purpose to approve updates as they are detected as being needed, rather than download a vast amount of unnecessary downloads through following an "approve all" approach.
The project is developed in C#.
WSUS 2 or WSUS 3 does not support an official way to extract files.
GWC Core makes it easier four you. You'll find a class library and a very simple example. Enter a KB-Number, specify a target and wait a moment. Then you'll see the extractet files. ;-)