Paul and I tasted a strange new Argentinian white today, a blend of Malvasia and Sauvignon blanc with the label New Age. Malvasia particularly is not a grape that I have tasted much of, mostly white blends from Spain and Portugal. The wine that we tasted at lunch was really interesting, having had aromas of orange blossoms and citrus, bubbles to the point of effervescence, and flavors of sweet ripe orange, mineral, and a viscous texture.
Malvasia itself is the general name for a closely related group of varietals that are all genetically fairly similar. The most important specific grape is probably Malvasia bianca, which is responsible for white wines in Mediterranean companies.
Portugal has a number of grape varietals confusingly labeled Malvasia, one of which, Malvasia Candida, is also known as Malmsey, a grape used to make a sweet style of wine called Madeira. Madeira is a style of fortified wine that is made in a process that heats the wine to extremely high temperatures and lets it oxidize. Madeira is consequently famous for being practically indestructible; at auction you might find some extremely old vintages over a hundred years old. They can be really good wines (particularly popular prior to the Civil War in the South, being consumed generally with cigars), but not to everyone's taste.