A quick google turns up this description from the website of a manufacturer of said devices :
The earths magnetic field helps create the great taste of fresh fruits. During the long growing season, fruit is held in a relatively constant position in relation to the earths magnetic field, aligning the liquid particles much like tiny compass needles. This natural balance gives fresh picked fruit its smooth, natural flavor.
The delicate magnetic alignment of the liquid particles is destroyed during the crushing, straining, pasteurizing, fermenting and distilling used to manufacture beverages, and much of the smooth natural taste is lost. The traditional slow aging process of wine and distilled spirits allows the particles to once again become aligned by the earths magnetic field, but this process takes years, and dramatically increases the cost of the finished product.
So, remember theres a natural give and take, but that Vintage Express can fool Mother Nature and realign balance in moments, not years.
So according to their theory, If I pick two grapes side by side off the same vine, then shake one of the grapes like crazy, the shaken grape should taste like crap, because the particles aren't aligned anymore?
Now I aint no scientist, but i'm pretty sure that wine aging has to do with chemical reactions and not whether their taste particles are properly aligned along a north south magnetic line.
Pure snake oil, I wonder if the company is owned by one of the members of insane clown posse...