Spice – Does vanilla really bring out the flavour of other foods

I can't count the times I have heard that vanilla brings out the flavour of other foods. For example it "makes chocolate taste more chocolatey," etc… I have also heard that it's the only spice that does this (enhance the flavour of other spices/foods).

Is this true? If so, by what mechanism does it do this?

Here are some places online that mention this alleged property of vanilla without explaining how it works:

• "Vanilla is used for its sweetness and its ability to enhance other flavors." (eHow)
• "Vanilla delivers characteristic and complex flavor notes to hundreds of types of food. With fruit- and dairy-based products, it enhances flavor by cutting acid notes, bringing out creamy notes and rounding out flavor systems." (preparedfoods.com)
• "Add vanilla to give new 'life' to flavorless seasonal fruits or other foods that need a flavor boost. Did you know that chocolate by itself tastes 'flat' which is why it usually contains vanilla?" (vanilla.com)

• …Chocolate simply wouldn’t taste like chocolate without vanilla. “Chocolate tends to be somewhat dull on its own. Vanilla transforms it,” says Patricia Rain, author of a new book, Vanilla: A Cultural History of the World’s Favorite Flavor & Fragrance. “Vanilla
  really enhances the flavor notes of chocolate,” agrees John Scharffenberger, CEO of Scharffen Berger Chocolate Maker in Berkeley, CA, where they prize vanilla so highly that they grind whole vanilla beans with cocoa nibs to make their chocolates.

  (vegetariantimes.com)

• "Vanilla is one of those ingredients, like salt and fat, that complements and brings out the flavor of other ingredients." (Wiki Answers)