There is now a website for Margaritaville Rum which should be out soon. The Margaritaville in New Orleans is now serving the four different types of rum.
A short review is available at the Rum Trader blog:
Just a quick review of the first RUM product from Jimmy Buffett’s Margaritaville Spirits line. The “Classic Mojito” is part of a larger “Ready To Drink” product line which includes a number of flavored margarita pre-mixed beverages. Margaritaville Spirits has promised a full line of Margaritaville RUMs including Dark, Silver, Coconut, and Spiced RUM. The website has bottle photos and an announced street date of “Summer 2009”.