One of the many catalogs I receive is the Wine Enthusiast. On the inside cover of the catalog I received last week is a description of Symphony Stemware wine glasses which are supposedly "designed and shaped to enhance the best characteristics of every wine." Accompanying this claim is a map of the tongue with the following caption:

"The specially designed shape of each glass directs the flow of wine to the proper areas of your palate, emphasizing a wine's best qualities and creating a balanced taste for maximum enjoyment."

Symphony isn't the only company to use a tongue map to promote their glasses. Riedel uses the same gimmick in their marketing. The thing is, from what I understand, the tongue map is a completely bogus idea. The tongue is not divided into taste regions. And even if it were, no glass is going to be able to direct flavors to one specific area of the tongue.

An article from the August 2004 issue of Gourmet magazine ("Shattered Myths" by Daniel Zwerdling... I can't find a link to it), tackled the tongue-map myth at some length and thoroughly debunked it:

"The tongue map? That old saw?" scoffs Linda Bartoshuk when I reach her at her laboratory at the Yale Univerity School of Medicine. Bartoshuk has done landmark studies on how people taste. "No, no. There isn't any 'tongue map.'"
Wait a minute: When you sip Pinot Noir from the correct Riedel glass, won't it maximize the fruit flavors by rushing the wine to the "sweet" zone on the tip of your tongue? When you serve a Chardonnay with too much fruit, won't the correct glass balance the flavors by directing the wine to the "acid" spots near the middle? "Nope," Bartoshuk laughs. "It's wrong." She and other scientists have proved that you can taste salty, sweet, and bitter everywhere on the tongue where there are taste buds. "Your brain doesn't care where taste is coming from in your mouth," Bartoshuk says. "And researchers have known this for thirty years."

The Wikipedia article on taste buds also debunks the idea of the tongue map: "Contrary to popular understanding, taste is not experienced on different parts of the tongue. The 'tongue map myth' was based on a mistranslation of a German paper that was written in 1901 by a Harvard psychologist. Though there are small differences in sensation, which can be measured with highly specific instruments, all taste buds can respond to all types of taste."