My wife bought Spice Islands Pure Vanilla Extract today. It says it is 100% bourbon vanilla. So, I got curious and went searching on the Internet. My first guess was it was somehow related to the French Bourbon family. I didn't see that connection, but I didn't look too much farther after I found this link and read that it is a species of the vanilla bean.
Vanilla Bean Facts
Got anything to add, Mr. Chef, er, Jeff? ;-)