I've ordered the vegan wine, beer and liquor! Not every vegan worries about whether fish bladders are used in the processing of alcohol, and I don't look down on them for it. Even if you don't, though, you're bound to have lots of vegan guests at your wedding, so it's important to make sure that everyone's comfortable.
I'm providing the alcohol for the wedding, rather than the caterer. It saves money if your venue and caterer allow for that! So I found a great place to order for the PA/DE/MD/NJ area (Franks Union Wine store - www.frankswine.com), and Frank even helped me with checking on the veganness of certain suggested alcohols. He now knows Barnivore.com - you probably already knew about it yourself, though.
