Sigma offers a lens optimization software to tweak lens performance and focus which connects to lenses via a special USB doc. There is a very nice demo on Vimeo that shows how the Optimization Pro software works.
The video is very neat and illustrates some important and surprising points about lenses. AF Fine-Tuning allows lens focus to be shifted forward or backward. This feature is available on many high-end DSLRs. However, Sigma is the first to allow the shift to be applied according to focal-length. This obviously makes sense since focus is not always off by a constant amount.
The most important thing to understand though is that lens calibration done by software is done on the lens alone and there does not seem to be a way for the lens to apply calibration depending on which camera it is attached to. For people with a single camera, only software calibration would be needed. For users of multiple cameras, the software calibration will most likely be used to ensure the lens focuses the same way at all focal-lengths and then in-camera AF Fine-Tuning would make sure that the lens focuses properly on that particular camera.
The Sigma Optimization Pro software lets user specific an AF Fine-Tuning adjustment ±20. The units are unspecified, so this would have to set by trial-and-error. This will be rather tedious and time-consuming but there is little way to improve this without the possibility of tuning with the camera attached to the lens. The Sigma USB dock makes this obviously impossible since it takes the place of the rear lens cap.
The other thing to note is that lens performance as a compromise between AF speed and accuracy can also be tweaked. Something similar is possible for stabilization where the compromise seem to be between view stability and stabilization efficiency.
It is certainly awesome to see Sigma try such new thing and we cannot wait to see how this works in practice.