I think it was originally on the rumor board:
Changes All Around World Showcase
In the Mexico pavilion, a 50- to 60-seat tequila bar, including a history of the beverage, replaces a retail shop adjacent to the restaurant, opening in summer 2008. Also in summer 2008, the pavilion's waterfront Cantina de San Angel is expanding with more seating with optimal views of World Showcase, and will offer a new menu.
From this it doesn't look like it will be there until next summer maybe that is why CM don't know anything about it.