I bought and tried using FocusMagic but it did a very poor job of adjusting OOF images. Part of the problem with OOF or unsharp images is a lack of boundary contrast. I always make sure to up contrast before sharpening as doing this cuts the amount of sharpening in half and does a much better job of preserving image detail.
What is different with InFocus, used properly, is that it allows you to adjust what it calls the "micro contrast" which builds detail in the structure of the area by darkening midtones. It infills independently of any standard sharpening and so it does things that no sharpening software can do. At least it does what cannot be done with the latest versions of Noise Ninja, Dfine 2.0, Neat Image, DeNoise, and CS5's NR, all of which I tested with images two weeks ago as a separate NR evaluation.