My nephew is turning 21 next month and I'd like to make his cake like this one.  Question is how are the Absolute bottle supported?  Pillars?  Dowels? Any assistance from all you creative minds is greatly appreciated...

I would dowel and board the bottom tier after your final coat of frosting, and then cover it with your fondant or modeling chocolate.  Set the bottles on it, and these look like they were pushed in slightly to be more level with the cardboard, and then using royal icing, melted chocolate, or sugar glue on all the bottles, I’d add your second tier.

Best of luck!

Actually, to add to that, am I even glue the bottles down to the first tier, as well.