Not sure if it is still valid - when I asked about it I was told that it would be taken down last Sunday, but it is still there. Since it's an automated process you get your license within few minutes.
As for usefulness. Well, I'm analyzing my camera focusing issue right now. It is a mess, so I'm running lots of test to establish at least single sensor I can use safely. So far it seems that the software produced repeatable results with both daylight and artificial light (500w). My case is a bit extreme, so I can see how this software helps me.
As lots of people pointed out - calibration is not exact science and there are a lot of variables here. I would guess that using such software you can get a feel of your camera and lens performance, but it's unlikely you'd be able to adjust it to ideal conditions, especially zoom lenses.