It is working very well for me with my D800
My results with the Reikal FoCal software and testing process:
Executive summary: I have found it excellent and much better than when I have attempted to go through the process manually - mainly because it gives me extensive data to convince me that the adjustments are making a valid difference. When you are mucking around with something as critical as focussing, for me this confidence is what I need.
I downloaded the pro version of the software for the reduced price of £45 (see my post above), printed out the two targets, stuck one on the wall, set up camera and tripod, made sure target was very well lit then started through the software.
The PDF that comes with it is very well written and led me to tweak a couple of settings which may have been helping me with the results (I set it so that it did not automatically adjust for lighting adjustments - as I was in full control of them; and I also set it so that when it validated the target on every shot it optimised the target image hence taking account of any very slight movements - this is supposed to improve its analysis process).
With that done the process is to set your AF fine tune to zero, it then takes 1-4 shots and then asks you to set your AF fine tune to -20, it then takes another 1-4 shots, and then you set your autofocus to -10, and so on till it has anything up to 50 shots at different AF fine tuning settings. From this it can tell you which AF fine tune is getting you the best quality image. It then shows you the before (zero AF fine tuning), and the recommended AF finetuning and you can see the difference. Key for me was that it produces a graph as per below (this is the results for my 28-300mm at 300mm clearly showing why -8 is the correct AF fine tune):

This clearly shows that the quality really is best at the AF fine tune point it came up with and gets worse at the other points. Also you can see here that it is taking multiple shots at each point to account for variation in the focussing system. And this for me is the deal clincher as when I was attempting to do the same thing manually I would often get slightly spurious data at different AF fine tuning points that threw my whole confidence with the process. The only realistic way to get over that is to take a huge amount of data, take the averages at each data point (or some more advanced process), and then look at performance across these averages across AF fine tuning points. This is what the software does for you, quickly with a report and graphs to back it up plus an image per data point if you want to go and have a look between them. Additionally, as there is some variation between shots, the program gives you a confidence remark in the fit rating of all the data, and hence might warn you if the data was all over the place and it would be dangerous to reach any conclusions (e.g. low light, moving target, AF being very inconsistent for instance if too close to the target) - a further point to get confidence in the result and something you just can't get from manual pen and paper testing.
Essentially it has given me so much more confidence in the results than a non software based system that I see it as money very well spent particularly if you compare what it is offering to the competition.
Incidentally, my results were (2 lenses tested so far), my 105 nikon VRII is spot on no change needed (and I have a detailed report to prove it following about 10mins of testing!), my 28-300mm had a range of adjustments per focal length ranging from -8 at 300mm to +3 at 28mm, hence I have set it at about -4 overall as the best compromise considering issues are going to be more noticable at the long end with the shallower DOF. This data, however has brought home to me the issue with zooms generally in that they have a range of performances that can not, at present be easily compensated for at their different focal lengths.
Other observations with the software:
0. It helps you set everything up quickly and effectively at the begining of the testing - for instance it immedeatily warned me that I had forgotton to set AF-S and single shot, and also told me how to move the target around so it is parrallel, correct height, acceptable distance (which it measures). Awesome.
1. Occassionally in the middle of the testing (say 20 shots in), it would throw out an error saying the results were being too inconsistent and did I want to abort the test?Initially i did, then I realised that if I ignored the message, about 3 shots in the warning went away and it went back to giving me an "Excellent Data Fit Quality" with the results. I could also see from the graph that its prediction made a lot of sense.
2. At the moment you can only do the test on the central focus point - for canon cameras you can test others. Don't know if it is a nikon SDK issue, or just not developed yet, but that could be very useful.
3. The software does a load of other testing for you such as measure consistency with AF, dust spot analysis and which Appertures it is likely to be a problem at, what your optimum apperture is for image quality - none of which I have tested yet, but could prove useful
4. The only manual bit of the "automatic" process for us Nikon users is having to set the AF fine tuning between each set of shots, this is not as good as it being automatic (though nikon's SDK is to blame for this), however the whole process is way better than doing it manually with your own charts and note taking.