at surplussched they sell adapter mount for M42 (T-mount) to most mount (about 15$ each)
http://www.surplusshed.com/pages/item/m1610d.html
unfortunately this is not usefull for us as we are looking for the reverse.
But i got some of these and there is an interesting thing in them.
the adapter is made from two part.the one emulating the mount (nikon,canon, pentax) and a ring that goes inside the adapter with the M42 thread.
If you can build the same kind of adapter but in reverse.
a M42 (or any other specs.) adapter that can receive a ring with all the differents mount, you could sale a one-for-all adapter.
the user would just need to change the ring according his needs.
these adapter are still usefull if you want to mold the shape of the mount without using expensive lenses.

For the magnet stuff, i think the fact that the power of magnet is not linear is an advantage. the closer they are the strong the force is, so there is no risk of "bumping" the two piece.
for the alignement, i do not think this is a problem , since you can find "levitation" gadget using the same principle and they do not look like hi-tech tool machining.
and finally it is ok the have the center pice trying to escape the force field, since that is helping the gg to stay into the focal plane..
a solution for controlling the stuff would be to have magnet on one side (the center ring) and electro-magnet (coil) on the outer ring, so you can even modulate the voltage to create the vibration. This way you can even generate a patterned movement (circle, flower square).

"and electro-magnet (coil) on the outer ring, so you can even modulate the voltage to create the vibration."

That will only move it on the Z axis or whatever plane you guys call the one that goes through the lens. Electromagnetic force acts perpendicular, not parallel. We just worked with exactly what you're talking about in physics class.

I don't know, the whole magnet thing seems extremely difficult to pull off. I've worked with magnets a lot lately and really don't see this working.

I encourage you all to prove me wrong though! :) lol.