Already happening!
They 'walk' on pads similar to walking a Giant Earth Mover (think 'Big Muskie' or the 'GEM of Egypt', only these drilling rigs are a bit smaller).
Four pads around the substructure of the rig are used to move the substructure, derrick, draw works, doghouse, etc. from one wellhead to another on the pad. Usually the distance between wellheads is on the order of 30 feet, and the walk (with the derrick full of drill pipe) takes about half a day.
The mud tanks, light plant, and pumps remain in situ. Mud return to the shale shakers is accomplished with a manifold which can be extended out as far along the pad as the rig is moved.
The pumps are attached by lines which can be added to or shortened as needed, as are the accumulator lines for the BOP. Electrical cables are kept on a trolley system which allows them to be extended or retracted in an orderly fashion.
The BOP stack is moved to the active wellhead as the previously actively drilling wellhead is capped, and the stack is pressure tested as required by law before drilling.
Rig moves happen after a casing run, drilling all of the vertical and curve sections of the wells on the pad and running intermediate casing before changing out drill strings and drilling the laterals.
This allows a number of wells to be drilled from a relatively small pad, the wells go out in different directions below the Last Charles Salt, usually somewhere in the Lodgepole Formation, and are steered to fit the drilling plan.
This way, four wells can be drilled with about 9500 feet of lateral in the target for a 1280 acre (two section) spacing.
Considering there are currently three levels of interest: the Middle Bakken (between the upper and lower Bakken Shales), the upper Three Forks (aka: "First Bench"), and in some areas, the Three Forks some 50+ feet below the top (aka:"second bench"), that makes 8 to 12 wells per lease with between 76,000 and 114,000 feet of 6-inch diameter wellbore through productive rock, if all goes well while steering the well.
In the 'bad old days', on a 160 acre spacing, eight vertical wells could be drilled in the same lease space, with a whopping 160 or so feet of Bakken exposure, and 800 feet of combined first and second bench Three Forks exposed.
It is a huge difference, and though the oil has been there and noted, and even produced in a few wells on the Nesson Anticline, the Billings Nose, and the Sannish Field, the technology has made production possible on the scale it is, with the Bakken topping 1 billion barrels of oil produced just recently, and still going strong.
The positive impact is that (aside from oil production) multiple wells can be drilled from one location, reducing the 'footprint' of the wells. Similarly, production facilities take up less room overall, are centrally located, and that cuts down on feeder pipelines and road needed. One rig move from pad to pad requires trucking and complete rig down as opposed to four moves from well to well, and drill strings only need to be changed out once on the pad. So costs are cut, and time is saved.
As ever, those changes have some impact on other specialized areas, and the rig move companies, trucking, and laydown crews (who specialize in laying down the 30 ft. sections of drill pipe) have had less business, but everyone else seems to be running pretty much at capacity.