The first 3 numbers specify the rotation axis and the fourth number is the number of degrees to rotate.
The rotation axis goes through local origin and the specified point. Using 1, 0, 0 or 0, 1, 0 as the first 3 numbers will rotate around the other 2 axes. I believe the tip explaining the numbers is displayed in the status bar when the mouse is over the transformation item.
In version 2010, you can also rotate an object with a two arrows in the toolbar above the 3D scene. Rotation axis in this case depends on the camera.