Vetiver in a perfume signals a woody note, although it is not a wood type at all but grass. Vetiver grows in India, Thailand, China, Java, Haiti and the island of Réunion (a small island outside of Madagascar – the main things I remember from a trip there 15 years ago was that there was a lot vanilla everywhere, an active vulcano and amazing fruit). The oil is brown and thick and the odor is sweet, amberesque and balsamic but also woody, smoky and earthy. The oil distilled in Haiti and Réunion has a more floral quality and is considered of higher quality. Haitian vetiver is appreciated but after the earthquakes in 2010 supply has changed drastically (affecting prices). If you look at the information about the notes in a perfume with vetiver you should be able to see where the vetiver in it comes from. For example Creed’s vetiver is haitian.
Also, I have to recommend this article by Clayton of What Men Should Smell Like about the Guerlain Vetiver Pour Elle because it is so very beautifully written.