It would be nice to use a magnetic coupling, but the power
transfer in these pumps is too much. The mag coupling has been around
for years and the vac pump manufacturers would be aware of it. Another
problem with magnets: they'd be close to the magnetic compass, being on
the back of the engine in most cases, and we have enough trouble with
magnetic fields as it is when we go to calibrate compasses.
"abripl"'s solution of an electric drive, especially if it's
away from the engine, is alright as long as he doesn't intend to fly
IFR, unless he has a vacuum-driven turn coordinator. Most TCs are
electric, and with attitude and heading gyros relying on an electrical
source all attitude info would be lost if the electrical system quit,
which they can do at the worst possible times. I haven't yet dealt with
the new glass panels, but would hope that they'd have some backup
power; the ones I see have peanut gyros in the panel as backups.

Dan