I know it's very similar to buildcraft and powercraft, and these are much more advanced... but that's my thing, I just love coding and wanted to do something like that. Furthermore I think it is much simpler and more straight-forward than those.
The mod adds Assemblies (Normal, Sorter, Furnace, Propeller, Counter, Chester, ...) and a Digger (aka Pac-Man :P)!
Read more at the HowTo page!
Old video, but explains the concept pretty good
New Video (showing some new features)