A recent study conducted by the University of Birmingham indicates elevated blood levels of magnesium and sulfate after bathing in epsom salts. However, there were no findings concerning the mechanism, or the therapeutic effects. [EDIT: Just noted this is the same study Uno posted above]

On a related note, here's a good article on aiding recovery after your workouts.

Uno: Please keep us updated if you find a good source for epsom salts