Here is the official write up, so now we can debate on what they mean by 'triple'... it even says one in the bottle so I'm imagining this beer is 1. primary, 2. secondary, and 3. bottle ... As far as adding more yeast later in the fermentation I am not familiar with this personally (but I don't know much) but I'm not sure this means that more yeast were added, it seems they just filter into a brightening tank (secondary) and then bottle prime. But it does say champagne and that could mean very 'dry' so maybe they do add more yeast - I'm sure others will know. Anyhow:
Since1994
TypeTriple fermentation Golden Ale, refermented in the bottle
Alcohol9 % alc./vol.
ColorBlond with a golden hue
TasteSmooth, slightly tart with the balanced flavors of wild spices, malt and hops
AromaWild spices
Shelf Life8 years or more
Serving SuggestionsGourmet dishes, fine cheeses and desserts
In February 1994, after 18 months of research, Unibroue launched La Fin du Monde (the end of the world). It is a 9 percent alcohol, triple fermentation beer. This type of beer was originally developed by the monks of the Middle Ages to be served on special occasions. La Fin du Monde is a deluxe beer made by triple fermentation and a unique way of straining the yeast. This method produces an unexpectedly subtle flavour. With its champagne-like effervescence, it has a vigourous presence in the mouth, which accentuates its strong personality. Slightly tart, with the balanced flavours of wild spices, malt and hops, it belongs to the class of great Trappist beers and, in this regard, is a North American first. At meals, it can replace white or red wines and enhances the flavour of most dishes. This beer is brewed to honour of the great explorers, who believed they had reached the end of the world when they discovered America.